# ChassisDex: full text > ChassisDex is a free, independent fitment and build-knowledge reference for the 2002-2007 Subaru Impreza WRX (GD/GG) and the 1990-2005 Mazda Miata (NA and NB). It is for owners, buyers and builders of those cars. It answers "will this part fit my car?" questions, lists known problems with causes and fixes, and groups modifications by goal, with every claim linked to its public sources and rated with a confidence tier and a last-verified date. Data last updated 2026-10-25; every fact below is as of that date. Coverage: 75 fitment answers, 29 known problems, 22 build entries, 98 sources. Confidence tiers: Confirmed = manufacturer document or 2+ independent sources agree; Reported = one reputable source; Limited = forum/anecdote/partial. Safety-critical parts (brakes, suspension, steering, restraints) are capped at Reported without a manufacturer document. Fitment is not guaranteed; verify before you buy. Please cite the page URL given with each entry. Corrections: hello@chassisdex.com. Short index: https://chassisdex.com/llms.txt ## Guides and comparisons ### Miata hardtop fitment (NA 1990-97, NB 1999-2005): what fits, latches, seals and OEM vs aftermarket URL: https://chassisdex.com/mazda-miata/hardtop-guide/ (published 2026-10-22, updated 2026-10-25) Question: Will an NA Miata hardtop fit an NB, and will an NB hardtop fit an NA? Short answer: Yes, NA and NB factory hardtops fit both generations: Mazda used the same basic shell from 1990 to 2005. The hardware may not match: a 1992-97 NA top needs an NB-style defroster pigtail on an NB (and an NB top the NA-style one on an NA); cars built from November 1, 2002 use redesigned front latches and strikers, so the top's latches must match the car; and cars that never had a hardtop may need side strikers and rear deck bolts. NC hardtops do not fit. Most owners recommend a used Mazda top over aftermarket ones. - Q: Will an NA Miata hardtop fit an NB? A: Yes. The shell is the same shape. For a 1992-97 top with a heated rear window you need an NB-style defroster pigtail (the Miata.net FAQ gives Mazda part NC11-67-060A), and on a car built from November 2002 on you need late-style front latches. The rear L-brackets on NA tops are shorter, so check they still press on a folded NB soft top. - Q: Will an NB hardtop fit an NA Miata? A: Yes, it is listed as a direct fit, but swap the defroster pigtail to use the heated glass, and if the top came from a car built from November 2002 on, fit 1990-2002 style front latches so they match the NA's strikers. - Q: What changed on the 2003 Miata hardtop latches? A: Mazda redesigned the front latches and the strikers on the windshield header for cars built from November 1, 2002, part way through the 2003 model year. Early-2003 cars built before that date have the old style. Check the build month on the driver's door-jamb label, not the model year. - Q: What hardware does a car need to mount a factory hardtop? A: Two front latches (on the top) that match the windshield strikers, two side latches on the top plus two side strikers on the car behind the doors, two rear deck bolts the back of the top slides onto, sound weatherstrips, and a defroster pigtail that matches the car. Side strikers bolt through the trim panel into nuts already welded into the body. - Q: Are aftermarket Miata hardtops worth it? A: They should fit any NA or NB, but most use old-style latches and an NA-style defroster plug, owner feedback on several brands has been mixed, and they are often not much cheaper than a used Mazda top. Lightweight fiberglass race tops save a lot of weight but often ship without window, brackets or seals. - Q: How heavy is a factory Miata hardtop? A: Roughly 40 to 50 lb depending on year, per figures attributed to the Miata.net FAQ. It is a two-person lift for most people. - Q: Are NA and NB hardtop weatherstrips the same? A: Mostly, but one owner found the B-pillar corner seal differs: NA seals left a gap (wind noise, some water) on an NB, and NB-specific seals closed it. Side-window and rear-deck seal sets are sold for all 1990-2005 tops. - Q: Does an NC hardtop fit an NA or NB? A: No. The NC is a larger, different body, and listings that say a top fits all Miatas normally mean NA and NB only. ### Miata wheel fitment (NA 1990-97, NB 1999-2005): bolt pattern, factory sizes, 15x7 to 15x9 offsets and brake clearance URL: https://chassisdex.com/mazda-miata/wheel-fitment-guide/ (published 2026-10-23, updated 2026-10-25) Question: What wheels fit an NA or NB Miata? Short answer: Every NA and NB Miata uses a 4x100 bolt pattern with a 54.1 mm hub bore and M12x1.5 studs, so NA, NB and ND wheels interchange; NC wheels (5x114.3) do not. Factory wheels run +40 to +45 offset. Common wider setups: 15x7 +35 to +38 (bolt-on), 15x8 +34 to +36 (bolt-on with sensible tires), 15x8 +25 to +28 with a 205/50R15 (may need a fender roll when lowered) and 15x9 +35 (coilovers, a roll and camber). 14-inch wheels do not clear the larger NB Sport brakes (2001-02 Sport, all 2003-05). - Q: What is the Miata NA and NB bolt pattern? A: 4x100 on every 1990-2005 car, with a 54.1 mm center bore and M12x1.5 lug studs. Most aftermarket 4x100 wheels have a 67.1 or 73.1 mm bore, so hub-centric rings are used to center them. - Q: What size are the factory NA and NB wheels? A: NA: 14x5.5 or 14x6 at +45, with 15x6 +45 on some special editions. NB: 14x6 on 1999-2000 base cars (one guide says +45, another +40), 15x6 +40 on 1999-2000 Sport and 2001-03 base cars, 16x6.5 +40 on 2001-03 Sport/SE and all 2004-05, and 17x7 +40 on the Mazdaspeed MX-5. - Q: Will 15x8 +25 or +28 wheels fit a stock Miata? A: Usually yes with a 205/50R15. Guides and owners agree the NA is tighter than the NB: on a stock-height NA it may just fit, and a light fender-lip roll plus about -1.5 degrees of camber is recommended once the car is lowered or on coilovers with more bump travel. NBs are more forgiving. - Q: What is the easiest wide wheel to fit on an NA Miata? A: A higher-offset 15x8 (+34 to +36, the 949 Racing 6UL sizes) sits further inboard than a +25. An old SuperMiata fitment table says 195/45 to 225/45 tires fit on standard-length dampers without rubbing, with 225/50 needing liner trimming and a roll on an NA. - Q: Do NA wheels fit an NB Miata? A: Yes on cars with the standard brakes (1999-2000 and most 2001-02 base cars). 14-inch wheels do not clear the larger Sport brakes on 2001-02 Sport-package cars and all 2003-05 cars; most 15-inch wheels do, but check the spoke design. - Q: Do 15x9 wheels fit a Miata? A: With work. A 15x9 +35 with a 225/45R15 is a common track size, but wheels that wide hit the factory front spring perch, so coilovers with narrow springs are required, plus a fender roll and at least about -1.5 degrees of camber. - Q: Do ND or NC Miata wheels fit an NA or NB? A: ND wheels do (4x100, 54.1 mm), though their +45 offset and taller tires look awkward and read the speedometer low. NC wheels do not: the NC uses 5x114.3. ### 2002-07 WRX and STI bolt pattern: 5x100 vs 5x114.3, which years, and how to convert URL: https://chassisdex.com/subaru-wrx/gd/bolt-pattern/ (published 2026-10-22, updated 2026-10-22) Question: What bolt pattern does a 2002-2007 Subaru WRX have? Short answer: Every US-market 2002-2007 Impreza WRX (bugeye, blobeye and hawkeye) and the 2004 STI use 5x100. Only the 2005-2007 STI uses 5x114.3. All of them share a 56.1 mm hub bore and M12x1.25 studs, so the bore does not tell you which wheels fit. To run 5x114.3 wheels on a 5x100 GD you either swap to 2005-07 STI hubs (the OEM route) or use hub-centric adapters. - Q: What is the bolt pattern of a 2002-2007 Subaru WRX? A: 5x100 (five studs on a 100 mm circle) for every model year, with a 56.1 mm center bore and M12x1.25 studs. Factory wheels were 16x6.5 +53 on 2002-05 cars and 17x7 +55 on 2006-07 cars. - Q: Did the 2005 WRX switch to 5x114.3? A: No. The switch in 2005 was the STI only. The WRX stayed on 5x100 through 2007. Posts and listings that say the 2005 WRX changed are mixing the two up. - Q: Do 2005-2007 STI wheels fit a GD WRX or a 2004 STI? A: Not directly: they are 5x114.3 and the WRX and 2004 STI hubs are 5x100. You need either the 2005-07 STI hub conversion or 5x100-to-5x114.3 adapters. Spacers alone do not change the bolt pattern. - Q: Do 2004 STI wheels fit a WRX? A: The bolt pattern and hub bore match (5x100, 56.1 mm), so they bolt on. The 2004 STI wheel is 17x7.5 +53. Sources do not confirm tire or brake clearance on every WRX, so check before you buy. - Q: Are 5x100 to 5x114.3 adapters safe? A: Quality hub-centric adapters from a known maker, torqued correctly and re-checked, are widely used. They push the wheel out by their thickness, add a second bolted joint and load the wheel bearing further outboard, and thin 15 mm ones need wheels with stud pockets. Cheap non-hub-centric adapters are not worth the risk. This is safety-critical; have the install checked. - Q: What does the STI 5x114.3 hub conversion involve? A: Front 2005-07 STI knuckles with their bolt-in hub units and matching front struts, STI 5x114.3 rear hubs and bearings pressed into the existing rear knuckles, plus rotors, dust shields and a 5x114.3 spare. Check front axle seating; some owners needed a CV spacer. See the hub conversion answer. - Q: How do I check which bolt pattern my car has? A: Pull a wheel and measure the hub studs, not the wheel: measure center to center from one stud to the second stud along (skip one). About 95 mm means 5x100; about 109 mm means 5x114.3. ### Mazda Miata NA (1990-97) vs NB (1999-2005): differences, known problems and which parts swap URL: https://chassisdex.com/mazda-miata/na-vs-nb/ (published 2026-10-25, updated 2026-10-25) Question: Which is better, an NA or an NB Miata? Short answer: It depends on what you want from the car. A 1994-97 NA gets the 1.8L, the larger 7-inch rear differential and an optional Torsen limited-slip; 1990-93 cars have the 1.6L, and 1990 to early-1991 cars should be checked for the short-nose crank. Every NB has a 1.8L; 2001-05 NB2 cars add variable valve timing and a regular 6-speed option, later cars get larger Sport brakes, and 2004-05 brought the Mazdaspeed turbo. Check 1999-2000 NB1 cars for coil packs and thrust bearings. Wheels and factory hardtops interchange between the two. - Q: What is the difference between an NA and an NB Miata? A: The NA is the first generation (1990-97 in the US), with a 1.6L engine through 1993 and a 1.8L from 1994. The NB (sold from 1998 as a 1999 model, through 2005) has a 1.8L in every car, with variable valve timing from 2001 (NB2), a 6-speed that became a regular option for 2001, larger Sport front brakes on later cars and a turbocharged Mazdaspeed version in 2004-05. Both use a 4x100 wheel pattern and the same basic hardtop shell. - Q: Should I buy a 1.6 or a 1.8 NA Miata? A: It depends. The 1994-97 1.8 has about 15 hp more, the larger 7-inch rear differential, an optional Torsen limited-slip (viscous before 1994) and larger front brakes, the same size as a standard NB. The 1990-93 1.6 uses a 6-inch rear, and 1990 to early-1991 cars have the short-nose crankshaft, which Hagerty says affected about 1% of those cars. The 1.6 and 1.8 flywheel and clutch parts do not swap one at a time, but a complete 1994-2005 assembly fits a 1.6 car. - Q: What is the difference between an NB1 and an NB2 Miata? A: NB1 means 1999-2000 cars; NB2 means 2001-05. The NB2 engine adds variable valve timing and uses a different ignition system; sources report that NB1 coil packs wear out and can damage the catalytic converter. The 6-speed became a regular option for 2001. In the last two years 16-inch wheels were standard and the 6-speed cars got 3.90 rear gearing instead of 4.10, and the 2004-05 Mazdaspeed MX-5 added a turbo (about 178 hp). - Q: Do NB parts fit an NA Miata? A: Many do. Sources list NB wheels and the NB factory hardtop as direct fits, and the NB 6-speed, the 1994-2005 rear differential set, NB front brakes, NB sway bars and complete NB shock and spring assemblies as fits with extra parts or work. The NB radiator is listed as not compatible, and only the 1999-2000 coil pack is listed for 1996-97 NAs. Each answer, with its confidence tier, is in the table below. - Q: What should I check when buying an NA or NB Miata? A: On both: rust (clogged body and soft-top drains, and on East Coast NBs the front side-members), oil leaks, and timing-belt history. On a 1990 to early-1991 car, look for crank-pulley wobble (short-nose crank). On a 1999-2000 NB, listen for thrust-bearing rattle and check the coil packs; 2001-02 NBs can have clutch chatter, and NB radiators have plastic end tanks that go brittle. ### 2002-05 Subaru WRX (EJ205) vs 2006-07 WRX (EJ255): differences, known problems and wheels URL: https://chassisdex.com/subaru-wrx/gd/2002-05-vs-2006-07/ (published 2026-10-25, updated 2026-10-25) Question: Which is better, a 2002-05 WRX or a 2006-07 WRX? Short answer: It depends on which engine risks you would rather manage. 2002-05 cars (bugeye 2002-03, blobeye 2004-05) use the 2.0L EJ205, where sources report rod-bearing wear tied to oil-change intervals, and a free-flowing downpipe can run a 2004-05 car lean on the stock tune. 2006-07 hawkeye cars use the 2.5L EJ255, which one source calls more prone to cracked ring lands from knock; head-gasket and valve-cover leaks are also reported, from limited sources. Every GD WRX is 5x100; factory wheels are 16x6.5 +53 (2002-05) and 17x7 +55 (2006-07). - Q: What are the bugeye, blobeye and hawkeye WRX? A: Nicknames for the three nose styles of the 2002-07 GD WRX: bugeye for 2002-03, blobeye for 2004-05 and hawkeye for 2006-07. In the US the 2002-05 cars use the 2.0L turbo EJ205 and the 2006-07 cars the 2.5L turbo EJ255. All of them use a 5x100 wheel bolt pattern. - Q: Is the EJ205 or the EJ255 more reliable? A: Sources do not name a clear winner. Rod-bearing wear is reported on the 2.0L EJ205 and linked to long oil-change intervals, cheap oil and wide factory bearing clearances; MotorTrend says the 2.5L engines see it less. Cracked ring lands from detonation can affect both, and one source says the 2.5L is more susceptible. For both, the sources advise quality oil changed often, good fuel and a conservative professional tune. - Q: What should I check on any 2002-07 WRX before buying? A: Timing-belt history (Subaru's interval is reported as 105,000 miles or 105 months, and the engine is interference type), the oil-feed screens that can starve the turbo (a P0011 code is a warning sign), a crunchy third gear, clutch hydraulics on a 2002 car (a restrictor valve was added for 2003), and thin paint. Ticking under load is usually normal on these engines. - Q: Did the bolt pattern change between the 2002-05 and 2006-07 WRX? A: No. Every 2002-07 GD WRX uses 5x100 with a 56.1 mm hub bore; only the 2005-07 STI changed to 5x114.3. Factory WRX wheels grew from 16x6.5 +53 to 17x7 +55 for 2006. See the WRX GD bolt pattern guide. ## Subaru WRX (GD/GG, 2002-2007) URL: https://chassisdex.com/subaru-wrx/gd/ Years: 2002-2007. Trims: WRX sedan (GD) and wagon (GG); WRX TR and WRX Limited added for 2006. STI (2004-07) is a separate model and only appears here where it is a parts donor. Engine: 2002-2005 US: EJ205 2.0L turbo. 2006-2007 US: EJ255 2.5L turbo. Notes: Three nose styles: 2002-03 'bugeye', 2004-05 'blobeye', 2006-07 'hawkeye'. US WRX uses 5x100 bolt pattern throughout. Sources: https://grassrootsmotorsports.com/articles/buyer-guide-2002-07-impreza-wrx/ ; https://www.radiumauto.com/cdn/shop/files/19-0299.pdf ### GD fitment answers #### What is the factory spec for the OEM 2002-2005 WRX wheel (16x6.5 +53) on a Subaru WRX (GD/GG, 2002-2007)? URL: https://chassisdex.com/subaru-wrx/gd/will-oem-wrx-wheel-16-fit/ Answer: Factory specification. Factory wheel spec for 2002-05 WRX: 5x100 bolt pattern, 56.1 mm centerbore, 16x6.5 at +53 offset, 205/55R16 tires. Two independent wheel-spec sources agree. Verdict: Specification. Years: 2002-2005. Applies to: all WRX. Confidence: Confirmed (3/3). Added 2026-10-19, updated 2026-10-19, sources last read 2026-10-15. Sources: FastWRX ; ThreePiece.us #### What is the factory spec for the OEM 2006-2007 WRX wheel (17x7 +55) on a Subaru WRX (GD/GG, 2002-2007)? URL: https://chassisdex.com/subaru-wrx/gd/will-oem-wrx-wheel-17-fit/ Answer: Factory specification. Factory wheel spec for 2006-07 WRX: 5x100, 56.1 mm centerbore, 17x7 at +55, 215/45R17. A forum spec compilation and a retailer page agree. Verdict: Specification. Years: 2006-2007. Applies to: all WRX. Confidence: Confirmed (3/3). Added 2026-10-19, updated 2026-10-19, sources last read 2026-10-15. Sources: FastWRX ; NASIOC forum #### Will 2004 STI wheel (17x7.5 +53, 5x100) fit a Subaru WRX (GD/GG, 2002-2007)? URL: https://chassisdex.com/subaru-wrx/gd/will-sti-2004-wheel-fit/ Answer: Yes. The 2004 US STI was the only STI on the WRX bolt pattern (5x100, 56.1 mm hub), so its wheels match a WRX hub. This is a bolt-pattern/hub match only. Sources do not address brake-caliper clearance on non-Brembo WRX brakes or tire clearance; check both. Verdict: Reported to fit. Years: 2002-2007. Applies to: all WRX. Confidence: Confirmed (3/3). Added 2026-10-19, updated 2026-10-19, sources last read 2026-10-15. Sources: FastWRX ; ThreePiece.us ; NASIOC forum #### Will 2005-2007 STI wheel (17x8 +53, 5x114.3) fit a Subaru WRX (GD/GG, 2002-2007)? URL: https://chassisdex.com/subaru-wrx/gd/will-sti-2005-wheel-fit/ Answer: No. 2005-07 STI wheels are 5x114.3, WRX hubs are 5x100. They do not bolt on without converting to STI hubs/bearings. Sources warn used listings labelled 'GD STI wheel' can be either pattern, and that spacers are not a real conversion. Verdict: Does not fit. Years: 2002-2007. Applies to: all WRX. Confidence: Confirmed (3/3). Added 2026-10-19, updated 2026-10-19, sources last read 2026-10-15. Sources: Grassroots Motorsports (Feb 2009 issue) ; FastWRX ; ThreePiece.us #### Will Aftermarket 5x100 / 56.1 mm wheels (BRZ/86-pattern) fit a Subaru WRX (GD/GG, 2002-2007)? URL: https://chassisdex.com/subaru-wrx/gd/will-brz-pattern-wheels-fit/ Answer: Yes, reportedly. One retailer article says BRZ/86 wheels share the 5x100 pattern and 56.1 mm hub with the GD, so wheels made for that chassis bolt on. Single source; offset, width and caliper clearance still need to be checked for your setup. Verdict: Reported to fit. Years: 2002-2007. Applies to: all WRX. Confidence: Reported (2/3). Added 2026-10-19, updated 2026-10-19, sources last read 2026-10-15. Sources: ThreePiece.us #### Will 2004-2007 STI front Brembo calipers fit a Subaru WRX (GD/GG, 2002-2007)? URL: https://chassisdex.com/subaru-wrx/gd/will-sti-brembo-front-fit/ Answer: Yes, with extra parts or work. A forum post says all 2004-07 STI front Brembos bolt to any 2002-07 WRX front, using 2004 STI rotors so the 5x100 lug pattern matches, and dust shields must be removed or drilled. Note: the 2009 Grassroots buyer guide calls the STI brake swap 'much more difficult' because of spindle/bearing/bolt-pattern differences; that likely concerns 2005+ STI parts but the sources do not say. Unresolved conflict; community-reported, not manufacturer verified. Verdict: Fits with extra parts or work. Years: 2002-2007. Applies to: all WRX. Confidence: Reported (2/3); safety-critical. Added 2026-10-19, updated 2026-10-19, sources last read 2026-10-15. Sources: ClubWRX forum ; Flatirons Tuning ; Grassroots Motorsports (Feb 2009 issue) #### Will 2004-2007 STI rear Brembo calipers fit a Subaru WRX (GD/GG, 2002-2007)? URL: https://chassisdex.com/subaru-wrx/gd/will-sti-brembo-rear-fit/ Answer: Yes, with extra parts or work. 2002-05 cars: reported to need an adapter bracket (sources name Kartboy and a KNS-005 bracket). 2006-07 cars: reported to use the existing brackets with no adapter bracket; one vendor notes the Brembo bolts have a different thread pitch than stock. Both generations: the smaller WRX parking brake needs a solution (adapter rotors, or KNS-800 shoes per one vendor). Community/vendor reports only; not manufacturer verified. Verdict: Fits with extra parts or work. Years: 2002-2007. Applies to: 2002-05 and 2006-07 differ (see notes). Confidence: Reported (2/3); safety-critical. Added 2026-10-19, updated 2026-10-19, sources last read 2026-10-15. Sources: ClubWRX forum ; Flatirons Tuning #### Will DBA 2657 rear adapter rotor fit a Subaru WRX (GD/GG, 2002-2007)? URL: https://chassisdex.com/subaru-wrx/gd/will-dba-2657-rotor-fit/ Answer: Yes, reportedly. One forum poster names DBA 2657 as the adapter rotor that keeps the WRX parking brake working with STI rear calipers, and warns that plain 2004 STI rotors would leave the parking brake inoperative. Single forum source; confirm the part number with the vendor before buying. Verdict: Reported to fit. Years: 2002-2007. Applies to: all WRX with STI rear Brembos. Confidence: Limited (1/3); safety-critical. Added 2026-10-19, updated 2026-10-19, sources last read 2026-10-15. Sources: ClubWRX forum #### Will Subaru Legacy GT brakes fit a Subaru WRX (GD/GG, 2002-2007)? URL: https://chassisdex.com/subaru-wrx/gd/will-legacy-gt-brakes-fit/ Answer: Yes, with extra parts or work. The Grassroots guide says Legacy GT brakes are larger and bolt right on, but requires larger wheels. The guide does not give years, part numbers or caliper details, so treat as a lead to research, not a fitment answer. Verdict: Fits with extra parts or work. Years: 2002-2007. Applies to: model years not specified by source. Confidence: Limited (1/3); safety-critical. Added 2026-10-19, updated 2026-10-19, sources last read 2026-10-15. Sources: Grassroots Motorsports (Feb 2009 issue) #### Will Mishimoto top-mount intercooler kit fit a Subaru WRX (GD/GG, 2002-2007)? URL: https://chassisdex.com/subaru-wrx/gd/will-mishimoto-tmic-fit/ Answer: Yes, reportedly. Retailer listing states 2002-07 WRX (EJ205/EJ255) fitment, described as bolt-on, not for RHD cars. Vendor rating ~350 whp. Retailer-stated fitment; no independent confirmation was found. Verdict: Reported to fit. Years: 2002-2007. Applies to: all WRX (not RHD). Confidence: Reported (2/3). Added 2026-10-19, updated 2026-10-19, sources last read 2026-10-15. Sources: Real Street Performance (retailer) #### Will Torque Solution top-mount intercooler fit a Subaru WRX (GD/GG, 2002-2007)? URL: https://chassisdex.com/subaru-wrx/gd/will-torque-solution-tmic-fit/ Answer: Yes, with extra parts or work. Retailer listing shows 2002-07 WRX fitment. It also states that 2002-07 WRX needs an OEM or aftermarket 2008+ STI Y-pipe kit to complete the install, so budget for that part. Retailer-stated; listing was out of stock when read. Verdict: Fits with extra parts or work. Years: 2002-2007. Applies to: all WRX. Confidence: Reported (2/3). Added 2026-10-19, updated 2026-10-19, sources last read 2026-10-15. Sources: Real Street Performance (retailer) #### Will Radium Engineering dual catch can kit fit a Subaru WRX (GD/GG, 2002-2007)? URL: https://chassisdex.com/subaru-wrx/gd/will-radium-catch-can-19-0299-fit/ Answer: Yes. The part maker's instruction sheet covers 2002-03 EJ205, 2004-05 EJ205 and 2006-07 EJ255 with separate steps for each, and notes a 1/2 in (13 mm) turbo inlet barb is assumed. Read the sheet for your year. Verdict: Reported to fit. Years: 2002-2007. Applies to: EJ205 and EJ255. Confidence: Confirmed (3/3). Added 2026-10-19, updated 2026-10-19, sources last read 2026-10-15. Sources: Radium Engineering (part manufacturer) #### Will 2008+ STI top-mount intercooler (OEM) fit a Subaru WRX (GD/GG, 2002-2007)? URL: https://chassisdex.com/subaru-wrx/gd/will-sti-08-tmic-fit/ Answer: Yes, with extra parts or work. Forum owners report the 2008+ STI top-mount fits a GD only after bracket changes, possible wastegate-actuator clearance issues, and swapping to the older-style BPV/hose. Anecdotal; the thread includes owners of earlier-chassis Imprezas as well, so check whether details apply to a GD. Verdict: Fits with extra parts or work. Years: 2002-2007. Applies to: 2002 owner report. Confidence: Limited (1/3). Added 2026-10-19, updated 2026-10-19, sources last read 2026-10-15. Sources: RS25 forum #### Will EJ205-era turbocharger (TD04L family) fit a Subaru WRX (GD/GG, 2002-2007)? URL: https://chassisdex.com/subaru-wrx/gd/will-ej205-turbo-fit/ Answer: Unclear. A Reddit thread says an EJ205-era turbo works on an EJ255 only if the compressor housing styles match (two different housings were used over the years), and one commenter says it would be undersized for max power. No definitive part-number mapping found. Verdict: Unclear — details missing. Years: 2006-2007. Applies to: EJ255 cars. Confidence: Limited (1/3). Added 2026-10-19, updated 2026-10-21, sources last read 2026-10-15. Sources: r/WRX #### Will WRX sedan 20 mm rear sway bar fit a Subaru WRX (GD/GG, 2002-2007)? URL: https://chassisdex.com/subaru-wrx/gd/will-sedan-rear-sway-20mm-fit/ Answer: Yes, reportedly. Grassroots tip: the wagon's 18 mm rear sway bar can be replaced with the sedan's 20 mm bar. Single editorial source; suspension part, so verify part numbers with a Subaru parts catalog first. Verdict: Reported to fit. Years: 2002-2007. Applies to: wagon (GG). Confidence: Reported (2/3); safety-critical. Added 2026-10-19, updated 2026-10-21, sources last read 2026-10-15. Sources: Grassroots Motorsports (Feb 2009 issue) #### Will Factory skid plates from Impreza-based Outback Sport fit a Subaru WRX (GD/GG, 2002-2007)? URL: https://chassisdex.com/subaru-wrx/gd/will-outback-sport-skidplates-fit/ Answer: Unclear. Grassroots says factory skid plates can be found on the Impreza-based Outback Sport in many junkyards. No year/part-number detail was given. Verdict: Unclear — details missing. Years: 2002-2007. Applies to: model years not specified by source. Confidence: Limited (1/3). Added 2026-10-19, updated 2026-10-21, sources last read 2026-10-15. Sources: Grassroots Motorsports (Feb 2009 issue) #### Will SKF VKMA 98115 timing belt kit (Subaru boxer DOHC) fit a Subaru WRX (GD/GG, 2002-2007)? URL: https://chassisdex.com/subaru-wrx/gd/will-skf-vkma-98115-fit/ Answer: Unclear. SKF's bulletin says this kit is for Subaru boxer DOHC engines in both turbo (WRX, STI) and non-turbo form, but the excerpt read does not list model years. Confirm against SKF's catalog. Verdict: Unclear — details missing. Years: 2002-2007. Applies to: check SKF catalog for your year. Confidence: Limited (1/3). Added 2026-10-19, updated 2026-10-21, sources last read 2026-10-15. Sources: SKF (part manufacturer) #### Will 2004-2007 US STI 6-speed manual transmission fit a Subaru WRX (GD/GG, 2002-2007)? URL: https://chassisdex.com/subaru-wrx/gd/will-sti-6mt-trans-fit/ Answer: Yes, with extra parts or work. Two NASIOC guides and a swap-kit vendor agree the STI 6-speed goes into a GD WRX with: the 6MT transmission mount (different from 5MT), STI shift linkage, 6MT clutch fork and a suitable driveshaft (WRX automatic shaft bolts to the R160; STI shaft needs a flange change). You can keep the WRX R160 and WRX hubs if you match the rear ratio to the gearbox (for example 3.90 gears with a 2004-05 box); the vendor calls keeping the R160 the simpler route. Front axles: 2002-early 2004 cars use female axles needing stubs; later cars use male axles. A standalone DCCD controller is optional. WRX clutch, flywheel and starter are reported to work. Verdict: Fits with extra parts or work. Years: 2002-2007. Applies to: manual WRX; parts list differs by year. Confidence: Confirmed (3/3). Added 2026-10-21, updated 2026-10-21, sources last read 2026-10-20. Sources: NASIOC forum ; NASIOC forum ; Flatirons Tuning (swap-kit vendor) #### Will STI R180 rear differential fit a Subaru WRX (GD/GG, 2002-2007)? URL: https://chassisdex.com/subaru-wrx/gd/will-sti-r180-rear-diff-fit/ Answer: Yes, with extra parts or work. Sources agree WRX rear axles do not fit the R180, so the swap brings STI rear axles, hubs and knuckles, rear brakes that suit them and a parking-brake solution. Driveshafts need a matching yoke (a NASIOC thread lists Subaru 38358AA000 to put a WRX auto shaft on an R180). Ratio must match the front: 3.90 for a 2004-05 STI box, 3.54 for 2006-07. Involves brakes and hubs, so capped at Reported. Verdict: Fits with extra parts or work. Years: 2002-2007. Applies to: only with STI rear axles, hubs/knuckles and matching rear brakes. Confidence: Reported (2/3); safety-critical. Added 2026-10-21, updated 2026-10-21, sources last read 2026-10-20. Sources: NASIOC forum ; NASIOC forum ; Flatirons Tuning (swap-kit vendor) #### Will COBB Accessport V3 AP3-SUB-001 fit a Subaru WRX (GD/GG, 2002-2007)? URL: https://chassisdex.com/subaru-wrx/gd/will-cobb-ap3-sub-001-fit/ Answer: Yes. COBB's manual and an authorized dealer both map AP3-SUB-001 to the 2002-2005 WRX; it does not fit 2006-07 WRX or any STI. The kit includes initialization connectors (blue for 2002, white for 2003-05). Flat-foot shift is not available on these cars (no electronic throttle). The dealer lists some dealer-replacement ECU part numbers as unsupported, so check your ECU label. Verdict: Reported to fit. Years: 2002-2005. Applies to: US-market 2002-2005 WRX (MT/AT). Confidence: Confirmed (3/3). Added 2026-10-21, updated 2026-10-21, sources last read 2026-10-20. Sources: COBB Tuning (product manufacturer; updated Apr 2024) ; AWD Performance Parts (COBB dealer) #### Will COBB Accessport V3 AP3-SUB-002 fit a Subaru WRX (GD/GG, 2002-2007)? URL: https://chassisdex.com/subaru-wrx/gd/will-cobb-ap3-sub-002-fit/ Answer: Yes. COBB's manual and an authorized dealer both map AP3-SUB-002 to the 2006-2007 WRX and 2004-2007 STI (plus some Forester XT / Legacy GT years). After a reflash the drive-by-wire throttle relearns; wait 5-10 seconds with the key on before starting. A device stays tied to one car until it is uninstalled. Verdict: Reported to fit. Years: 2006-2007. Applies to: US-market 2006-2007 WRX (also 2004-07 STI). Confidence: Confirmed (3/3). Added 2026-10-21, updated 2026-10-21, sources last read 2026-10-20. Sources: COBB Tuning (product manufacturer; updated Apr 2024) ; AWD Performance Parts (COBB dealer) #### Will 2015-2021 WRX (VA) factory wheels fit a Subaru WRX (GD/GG, 2002-2007)? URL: https://chassisdex.com/subaru-wrx/gd/will-va-wrx-wheels-fit/ Answer: No. Retailer spec tables agree the 2015+ WRX moved to 5x114.3 while the 2002-07 WRX uses 5x100 (both on a 56.1mm hub), so VA wheels do not bolt onto a GD WRX. Bolt-on 5x100-to-5x114.3 adapters are sold (for example 15mm hub-centric units), but one wheel retailer warns they push the wheel out by their thickness, add weight and hardware to re-check, and recommends converting to 2005+ STI hubs instead. On a 2005-07 STI (already 5x114.3) the pattern matches; check offset and brake clearance. Verdict: Does not fit. Years: 2002-2007. Applies to: GD WRX (5x100); 2005-07 STI already 5x114.3. Confidence: Confirmed (3/3). Added 2026-10-21, updated 2026-10-21, sources last read 2026-10-21. Sources: FastWRX.com (Mach V Motorsports, Subaru parts retailer) ; Element Wheels (wheel retailer) ; ThreePiece.us (wheel retailer blog) ; Oakos (retailer listing for an ISC Suspension product) #### Will 2008-2014 WRX (GH/GR/GV) factory wheels fit a Subaru WRX (GD/GG, 2002-2007)? URL: https://chassisdex.com/subaru-wrx/gd/will-gr-wrx-wheels-fit/ Answer: Yes, reportedly. FastWRX lists every 2008-2014 WRX wheel as 5x100 with a 56.1mm bore and +53 offset, the same pattern and bore as the GD WRX, and a second retailer agrees the 2008-14 WRX stayed on 5x100. One wheel blog instead says all 2008-14 WRX moved to 5x114.3; that conflicts with the two spec tables, so measure or check the wheel's stamping before buying. The 2011-14 17x8 wheels came with 235/45R17, wider than any GD WRX tire, so check clearance on lowered cars. Verdict: Reported to fit. Years: 2002-2007. Applies to: GD WRX and 2004 STI (5x100). Confidence: Reported (2/3). Added 2026-10-21, updated 2026-10-21, sources last read 2026-10-21. Sources: FastWRX.com (Mach V Motorsports, Subaru parts retailer) ; Element Wheels (wheel retailer) ; ThreePiece.us (wheel retailer blog) #### Will 2005-07 STI 5x114.3 hub conversion (front knuckles/hub units, rear hubs and bearings) fit a Subaru WRX (GD/GG, 2002-2007)? URL: https://chassisdex.com/subaru-wrx/gd/will-sti-0507-hub-conversion-fit/ Answer: Yes, with extra parts or work. This is the 'proper' way to run 5x114.3 wheels on a 5x100 GD, as opposed to adapters. An owner who did the full OEM conversion on a 2004 STI lists what it took: 2005-07 STI front knuckles with their bolt-in hub units, front struts that match the 2005+ knuckle mounting (the rear struts carried over), STI 5x114.3 rear hubs and bearings pressed into the existing rear knuckles, matching dust shields, rotors and a 5x114.3 spare. 2005-only knuckles also use a tie bar and longer bolts that 2006-07 knuckles do not need. Early 2004 STIs with female front axles needed extra transmission side parts. A second forum thread gives a similar list and mentions tone-ring spacers to keep the original axles, and an owner blog notes GD front axles may not seat fully in newer bolt-in hubs without an 8mm CV spacer, so confirm axle compatibility. Forum and blog sources only, and this is suspension/hub work, so it stays at tier 2: verify part numbers for your exact car and have it done or checked by a qualified shop. Verdict: Fits with extra parts or work. Years: 2002-2007. Applies to: GD WRX and 2004 STI (5x100); 2005-07 STI is already 5x114.3. Confidence: Reported (2/3); safety-critical. Added 2026-10-22, updated 2026-10-22, sources last read 2026-10-22. Sources: NASIOC forum (owner parts list with OEM part numbers, 2013, edited 2025) ; IGOTA~STi forum ; b.obsdian (owner build blog, 2021) ; ThreePiece.us (wheel retailer blog) #### Will 5x100 to 5x114.3 wheel adapters (hub-centric, 15-25 mm) fit a Subaru WRX (GD/GG, 2002-2007)? URL: https://chassisdex.com/subaru-wrx/gd/will-wheel-adapter-5x100-5x1143-fit/ Answer: Yes, with extra parts or work. Bolt-on 5x100 to 5x114.3 adapters are sold for the 2002-14 WRX, so 5x114.3 wheels (for example 2005-07 STI wheels) can go on a GD without changing hubs. They are hub-centric on the 56.1 mm Subaru hub and use M12x1.25 hardware, and they space the wheel out by their own thickness (15, 20 or 25 mm), which effectively lowers the wheel offset by that amount, so check fender and tire clearance. With thin (15 mm) adapters the factory studs usually poke out past the adapter face, so the wheel must have clearance pockets on its back side (one retailer says most STI wheels do) or the studs must be dealt with. A guide site points out the trade-off: the wheel load now passes through two bolted joints, the bearing is loaded further outboard, and both sets of nuts must be torqued and re-checked; cheap non-hub-centric adapters are a bad idea on a turbo AWD daily. The OEM alternative is the 2005-07 STI hub conversion. Retailer and guide sources only, safety-critical, so tier 2. Verdict: Fits with extra parts or work. Years: 2002-2007. Applies to: 5x100 cars: all GD WRX and the 2004 STI (2005-07 STI is already 5x114.3). Confidence: Reported (2/3); safety-critical. Added 2026-10-22, updated 2026-10-22, sources last read 2026-10-22. Sources: RallySport Direct (retailer product page) ; RallySport Direct (retailer product page) ; WRX Parts (guide site, updated Aug 2026) ; Oakos (retailer listing for an ISC Suspension product) #### Will 2005-09 Legacy GT factory wheel (17x7 +55, 5x100) fit a Subaru WRX (GD/GG, 2002-2007)? URL: https://chassisdex.com/subaru-wrx/gd/will-legacy-gt-0509-wheel-fit/ Answer: Yes, reportedly. The 2005-09 Legacy GT wheel is a 17x7 +55 on 5x100 with Subaru's 56.1 mm bore, which is the same size and offset a Subaru retailer lists for the 2006-07 WRX's own factory wheel, so it bolts on as an OEM-size swap. A NASIOC owner who fitted Legacy GT brakes to his WRX quotes the same 17x7 +55 spec, and a Subaru retailer's wheel-spec thread lists the 2005-06 and 2007-09 Legacy GT at 17x7 +55. On a 2002-05 WRX (16-inch from the factory) a 215/45R17 keeps the overall diameter close to stock. The retailer's thread warns factory Subaru wheels do not clear STI Brembo calipers unless stated. One buyer's thread cites a +48 figure for some Legacy-family wheels (that is the Outback size), so confirm the stamp on the back of the wheel. Retailer and forum sources; tier 2. Verdict: Reported to fit. Years: 2002-2007. Applies to: all GD WRX and the 2004 STI (5x100); not 2005-07 STI (5x114.3); does not clear STI Brembos. Confidence: Reported (2/3). Added 2026-10-23, updated 2026-10-23, sources last read 2026-10-23. Sources: FastWRX.com (Mach V Motorsports, Subaru parts retailer) ; RS25.com (maintained by a Subaru parts retailer, Mach V / FastWRX) ; NASIOC (2005 owner install write-up) ### GD known problems #### Cracked piston ring lands from detonation (2002-2007 (reported most often on 2.5L EJ255)) URL: https://chassisdex.com/subaru-wrx/gd/problems/ringland-failure/ Severity: High. Confidence: Confirmed. Updated 2026-10-19. Symptoms: Oil consumption rising, blow-by/crankcase pressure, smoke, loss of compression. Cause: Knock (detonation) hammers the thin ring land on the stock cast pistons. Sources list low-octane fuel, poor tuning, lean fueling and sustained hard driving as triggers; a tight ring gap is also mentioned as a contributor. One source notes the 2.5L is the more susceptible one; Grassroots says ring lands also go first on the 2.0L. Fix: Prevention matters most: good fuel, conservative professionally-built tune, healthy cooling and intake. Once ring lands crack the short block needs rebuilding. Sources: Grassroots Motorsports (Feb 2009 issue) ; Come and Drive It ; MotorTrend #### Rod-bearing wear on the 2.0L EJ205 (2002-2005) URL: https://chassisdex.com/subaru-wrx/gd/problems/ej205-rod-bearing-wear/ Severity: High. Confidence: Confirmed. Updated 2026-10-19. Symptoms: Rod knock, low oil pressure; bearing wear can be silent until a bearing spins, often under full boost near redline. Cause: Sources tie it to long oil-change intervals and cheap oil, and to the wide factory bearing-clearance tolerance. One shop reports it on stock, unmodified cars and says it is not caused by tuning. MotorTrend says the 2.5L engines see it less. Grassroots names the No. 2 rod bearing as a next-to-fail item. Fix: Short oil intervals with quality synthetic, periodic oil analysis and oil-pressure monitoring; budget for engine work before heavy modification of a high-mileage car. Sources: Innovative Tuning ; MotorTrend ; Grassroots Motorsports (Feb 2009 issue) #### Clogged oil-feed screens starving the turbo (P0011) (2002-2007 (EJ-powered)) URL: https://chassisdex.com/subaru-wrx/gd/problems/avcs-oil-screen-turbo-starvation/ Severity: High. Confidence: Reported. Updated 2026-10-19. Symptoms: P0011 (intake cam timing) code; turbo wear or failure. Cause: A turbo rebuilder reports small oil screens (AVCS banjo / turbo feed) clog with varnish from degraded oil; the passenger-side screen feeds both turbo and the intake AVCS solenoid, so the code can appear after the turbo has already run starved. Fix: The rebuilder says the specialist community recommends removing the screens on turbo EJs, and to fix the screen before fitting any replacement turbo. Verify against current guidance; the TSB numbers it cites were not independently checked. Sources: The Boost Lab #### Timing belt is an interference-engine risk; 105k mi / 105 months (2002-2007) URL: https://chassisdex.com/subaru-wrx/gd/problems/timing-belt-interval/ Severity: High. Confidence: Reported. Updated 2026-10-19. Symptoms: No warning on a belt failure; bent valves and piston damage follow. Cause: Subaru's schedule is reported as 105,000 miles or 105 months (time counts, not just distance). The engine is described as interference type by a shop checklist. Grassroots also lists 105k for the belt and plugs. Fix: Replace belt with tensioner, idlers and water pump as one job, using a new pump gasket. Confirm the interval in your owner's manual; this site did not read the manual itself. Sources: Grassroots Motorsports (Feb 2009 issue) ; ClubWRX forum ; Nashville Performance ; SKF (part manufacturer) #### Stock transmission/clutch is the fuse under extra power (2002-2007) URL: https://chassisdex.com/subaru-wrx/gd/problems/drivetrain-weak-link/ Severity: Medium. Confidence: Reported. Updated 2026-10-19. Symptoms: Clutch slip or failure, damaged synchros or gearbox after power-adder mods or hard launches. Cause: Grassroots says the clutch and transmission commonly act as the driveline's weak link, and that even light power modifications can destroy the stock WRX gearbox if driven hard; STI drivetrain is the strong option but a difficult swap. Fix: Budget for clutch and drivetrain upgrades along with power mods, and drive within the stock parts' limits. Sources: Grassroots Motorsports (Feb 2009 issue) #### Worn synchros (3rd gear) and cold-shift shudder (2002-2007) URL: https://chassisdex.com/subaru-wrx/gd/problems/worn-synchros-cold-shudder/ Severity: Low. Confidence: Reported. Updated 2026-10-19. Symptoms: Crunch going into third; shudder when cold. Cause: Reported by Grassroots as common on hard-driven cars. No root cause given beyond wear. Fix: Check on a test drive; a crunchy third suggests a tired gearbox. Reverse/first being stiff is described as normal. Sources: Grassroots Motorsports (Feb 2009 issue) #### Free-flowing downpipe can run 2004-05 WRX lean on stock tune (2004-2005) URL: https://chassisdex.com/subaru-wrx/gd/problems/exhaust-upgrade-lean-2004-05/ Severity: High. Confidence: Reported. Updated 2026-10-19. Symptoms: Lean air/fuel under boost; detonation risk. Cause: Grassroots warns that the 2004-05 WRX's stock software can let the engine run too lean after a free-flowing exhaust swap (and that on STI the stock turbo's wastegate may let boost run away). Fix: Pair exhaust changes with a professional tune; do not run catless/free-flow exhaust on the stock map. Sources: Grassroots Motorsports (Feb 2009 issue) ; MotorTrend #### Early clutch hydraulic durability (restrictor valve added 2003) (2002 (2003 revision)) URL: https://chassisdex.com/subaru-wrx/gd/problems/clutch-hydraulics-2002/ Severity: Low. Confidence: Reported. Updated 2026-10-19. Symptoms: Low or spongy pedal, hydraulic wear. Cause: Grassroots says the 2003 model year added a restrictor valve to the clutch hydraulics for better durability. It does not say why or how common failures were. (A Subaru bulletin on clutch master cylinders exists but covers 2015-20 WRX, so it is not used here.) Fix: Inspect and bleed the clutch hydraulics on a 2002 car; ask a Subaru specialist whether the updated parts apply. Sources: Grassroots Motorsports (Feb 2009 issue) ; Nashville Performance #### Ticking/clicking under load is usually normal (2002-2007) URL: https://chassisdex.com/subaru-wrx/gd/problems/exhaust-ticking-is-normal/ Severity: Info. Confidence: Reported. Updated 2026-10-19. Symptoms: Tapping or clicking under load. Cause: Grassroots says this is a side-effect of the engine's unusual exhaust layout, made louder by aftermarket exhaust/injectors or missing heat shields. Not a reason to walk away; still listen for real rod knock. Fix: None needed in itself. Compression-test modified cars. Sources: Grassroots Motorsports (Feb 2009 issue) #### Thin paint and thin sheet metal (2002-2007) URL: https://chassisdex.com/subaru-wrx/gd/problems/thin-paint-and-panels/ Severity: Low. Confidence: Reported. Updated 2026-10-19. Symptoms: Paint scratches easily; fenders and doors dent or wave easily; repainted bumpers/hoods are common. Cause: Grassroots reports thin paint and sheet metal on these cars. Fix: Inspect panels carefully when buying; don't lean on fenders. Sources: Grassroots Motorsports (Feb 2009 issue) #### Valve cover gasket oil leaks on the 2.5L EJ255 (2006-2007 (EJ255)) URL: https://chassisdex.com/subaru-wrx/gd/problems/ej255-valve-cover-gasket-leaks/ Severity: Low. Confidence: Limited. Updated 2026-10-20. Symptoms: Oil seepage at the valve covers, burning-oil smell or smoke from the engine bay. Cause: An enthusiast blog lists valve cover gaskets among common EJ255 problems and calls it normal age and mileage wear (typically past about 100k miles or 10 years), not a design flaw. Fix: Replace both valve cover gaskets; the blog calls it a moderate DIY job (coil packs and breather hoses come off). Rule this out before assuming a head gasket leak. Sources: 8020 Automotive (enthusiast blog) #### Head gasket leaks and head lifting on the 2.5L turbo (2006-07) (2006-2007 WRX (EJ255) and 2004-07 STI (EJ257)) URL: https://chassisdex.com/subaru-wrx/gd/problems/ej25-head-gasket-leaks/ Severity: High. Confidence: Limited. Updated 2026-10-22. Symptoms: Slow oil or coolant seepage along the seam where each cylinder head meets the block, coolant loss or overheating, boost that wanders, or a sweet coolant smell and white smoke on cold start. Cause: A repair-trade magazine says most EJ25 head gasket failures show up around 100k miles as slow leaks, and that detonation (more likely with more boost) can also kill turbo EJ25 gaskets. Owners and mechanics report the turbo 2.5L engines suffer this less often than the non-turbo EJ25s that made it famous; tuning shops on a 2006 forum thread blame warped heads, out-of-round cylinders or heads lifting under high cylinder pressure on modified cars. Sources are mixed and mostly anecdotal, so treat it as a risk to check, not a certainty. Fix: Rule out simpler causes first: valve cover gaskets (see the EJ255 valve cover entry), air in the cooling system, a bad overflow hose or cap. A shop can confirm with a cooling-system pressure test and a combustion (block) test. The proper repair is new head gaskets with the heads checked for flatness and resurfaced, new head bolts, and usually the timing belt, water pump and idlers at the same time. Keep the tune conservative to avoid detonation. Sources: Underhood Service (trade magazine for repair shops, Apr 2025) ; NASIOC forum (replies from tuning shops, 2006) ; r/subaru ### GD build entries by goal #### Reliability: Oil analysis and oil-pressure monitoring URL: https://chassisdex.com/subaru-wrx/gd/best-mods/reliability/#oil-analysis-and-pressure-monitoring Because EJ205 rod-bearing wear can be silent, one specialist recommends sending oil samples for analysis and watching oil pressure to catch trouble early. Analysis is not foolproof between changes. Caveats: Use the oil you normally run for samples. Single vendor source plus MotorTrend on oiling. Confidence: Reported. Updated 2026-10-19. Sources: Innovative Tuning ; MotorTrend #### Reliability: Inspect/remove AVCS and turbo oil-feed screens URL: https://chassisdex.com/subaru-wrx/gd/best-mods/reliability/#remove-oil-feed-screens A turbo rebuilder says the small screens in the oil-feed path clog on turbo EJs and should be addressed before replacing a turbo. Caveats: Engine-internal oiling work: have a Subaru specialist confirm. TSB numbers cited by the source were not verified. Confidence: Reported. Updated 2026-10-19. Sources: The Boost Lab #### Reliability: Have a professional tune when adding exhaust or boost parts URL: https://chassisdex.com/subaru-wrx/gd/best-mods/reliability/#professional-tune-with-bolt-ons Sources agree that detonation is the killer of these engines and that a careful tune matters; Grassroots notes staged power packages exist, and MotorTrend places much of the ring-land problem on fueling strategy rather than the pistons alone. Caveats: This site does not recommend a tuner. A tune is not a guarantee of engine safety. Confidence: Reported. Updated 2026-10-19. Sources: Grassroots Motorsports (Feb 2009 issue) ; MotorTrend ; Come and Drive It #### Reliability: Install a catch can for crankcase ventilation URL: https://chassisdex.com/subaru-wrx/gd/best-mods/reliability/#catch-can Radium sells a dual catch can kit with separate instructions for 2002-03 EJ205 and 2004-07 cars. Blow-by from damaged ring lands pressurizes the crankcase, which is why people watch this area. Caveats: The kit's own sheet is the fitment authority; whether a catch can prevents failures is not established by the sources. Confidence: Reported. Updated 2026-10-19. Sources: Radium Engineering (part manufacturer) ; Come and Drive It #### Reliability: Replace timing belt, tensioner, idlers and water pump together URL: https://chassisdex.com/subaru-wrx/gd/best-mods/reliability/#timing-belt-kit Shop and forum sources recommend doing the pump, tensioner and idlers with the belt because the labour overlaps. SKF's bulletin covers the Subaru DOHC kit including the pump gasket and tensioner priming. Caveats: Follow the factory service procedure. Torque specs differ by source; use the service manual. Confidence: Reported. Updated 2026-10-19. Sources: Nashville Performance ; ClubWRX forum ; SKF (part manufacturer) #### Cooling: Top-mount intercooler upgrade URL: https://chassisdex.com/subaru-wrx/gd/best-mods/cooling/#top-mount-intercooler Two retailer listings show 2002-07 WRX fitment. A vendor test on a ~305 hp car at 20-22 psi reported a 14 hp gain and 30°F lower intake temps versus the stock STI intercooler (vendor claim). Torque Solution notes a 2008+ STI Y-pipe kit is required for 2002-07 WRX. Caveats: Vendor figures are marketing claims. Check CARB legality for your state (Torque Solution lists 'No'). Confidence: Reported. Updated 2026-10-19. Sources: Real Street Performance (retailer) ; Real Street Performance (retailer) #### Wheels & tires: Better tires on wider wheels URL: https://chassisdex.com/subaru-wrx/gd/best-mods/wheels-tires/#wider-wheels-and-tires Grassroots calls this the best bang-for-the-buck upgrade for the standard WRX; the small stock 16x6.5 wheels limited grip. Wheel basics: 5x100, 56.1 mm hub; BRZ/86 wheels share the pattern per one retailer. Caveats: Never treat spacers as a substitute for the correct bolt pattern. Confidence: Reported. Updated 2026-10-19. Sources: Grassroots Motorsports (Feb 2009 issue) ; FastWRX ; ThreePiece.us #### Wheels & tires: Skid plates for rallycross/stage use URL: https://chassisdex.com/subaru-wrx/gd/best-mods/wheels-tires/#skid-plates-rally Grassroots points rally-bound owners to aftermarket skid plates and to factory Subaru plates from the Outback Sport. Caveats: No part numbers or years given by the source. Confidence: Limited. Updated 2026-10-19. Sources: Grassroots Motorsports (Feb 2009 issue) #### Suspension: Larger rear bar, better shocks, camber bolts URL: https://chassisdex.com/subaru-wrx/gd/best-mods/suspension/#rear-bar-shocks-camber Grassroots says most WRXs benefit from a larger rear anti-roll bar and better shocks, that the cars like more negative camber (aftermarket eccentric bolts), and that wagon owners can use the sedan's 20 mm rear bar. Caveats: Suspension is safety-critical: have alignment and parts verified by a professional. Confidence: Reported. Updated 2026-10-19. Sources: Grassroots Motorsports (Feb 2009 issue) #### Brakes: STI Brembo brake swap URL: https://chassisdex.com/subaru-wrx/gd/best-mods/brakes/#sti-brembo-swap Community and vendor sources describe front Brembos bolting to the WRX with the right rotors, and rears needing an adapter bracket on 2002-05 cars plus a parking-brake solution. Grassroots notes WRX rotors get hard use on track. Caveats: Brakes are safety-critical. All claims here are community-reported, not manufacturer-verified, and one source disagrees on difficulty. Follow a vendor's kit documentation. Confidence: Reported. Updated 2026-10-19. Sources: ClubWRX forum ; Flatirons Tuning ; Grassroots Motorsports (Feb 2009 issue) #### Drivetrain: STI 6-speed swap URL: https://chassisdex.com/subaru-wrx/gd/best-mods/drivetrain/#sti-6-speed-swap The usual answer when the WRX 5-speed is the weak link. Guides agree the cheapest route keeps the WRX R160 rear (re-geared to match) and WRX hubs; the full R180 route is stronger but pulls in STI axles, hubs and rear brakes. Caveats: Year-specific parts lists. See the fitment pages for both routes. Confidence: Confirmed. Updated 2026-10-20. Sources: NASIOC forum ; NASIOC forum ; Flatirons Tuning (swap-kit vendor) #### Power: ECU reflash with a COBB Accessport URL: https://chassisdex.com/subaru-wrx/gd/best-mods/power/#cobb-accessport Two different Accessport models cover the GD WRX: AP3-SUB-001 for 2002-05 and AP3-SUB-002 for 2006-07. Pair the map to your exact hardware or use a professional tune. Caveats: Can affect warranty and emissions compliance; pick the correct part number for your year. Confidence: Confirmed. Updated 2026-10-20. Sources: COBB Tuning (product manufacturer; updated Apr 2024) ; AWD Performance Parts (COBB dealer) ## Mazda Miata NA (1990-1997) URL: https://chassisdex.com/mazda-miata/na/ Years: 1990-1997. Trims: Single trim with option packages (A/B/C, later PEP/Leather/R package) and special editions; manual or 4-speed automatic. Engine: 1990-93: 1.6L BP-ZE. 1994-97: 1.8L (about +15 hp, OBD-II from 1996, 133 hp for 1996). Notes: Informally 'NA6' (1.6) vs 'NA8' (1.8). 1990 and early-1991 1.6 cars have the 'short-nose' crankshaft. Torsen LSD optional from 1994 (viscous LSD before that). Sources: https://www.hagerty.com/media/buying-and-selling/1990-97-mazda-miata-buyers-guide/ ; https://fixjunk.com/solomiata/solomiata/Drivetrain.html ### NA fitment answers #### Will NB 6-speed manual transmission (with NB shifter) fit a Mazda Miata NA (1990-1997)? URL: https://chassisdex.com/mazda-miata/na/will-nb-6speed-trans-fit/ Answer: Yes, with extra parts or work. Two sources agree the NB 6-speed bolts into a manual NA. You need the 6-speed donor's trans plate and shifter, the NA speedometer gear/cable replaces the NB electronic sensor, and only two of the three starter bolts are used. Gearing: the 6-speed is much steeper and in the US was paired with a 3.909 rear; one source says a 4.30 rear should be changed to 3.909 or at least 4.10. Verdict: Fits with extra parts or work. Years: 1990-1997. Applies to: manual NA. Confidence: Confirmed (3/3). Added 2026-10-19, updated 2026-10-19, sources last read 2026-10-15. Sources: Randy Stocker / SoloMiata (fixjunk.com) ; Redline Auto Parts (used-parts dealer; hands-on checks, own disclaimer) #### Will 1994-2005 differential, driveshaft and axles (7-inch rear) fit a Mazda Miata NA (1990-1997)? URL: https://chassisdex.com/mazda-miata/na/will-nb-diff-driveshaft-axles-fit/ Answer: Yes, with extra parts or work. Direct fit on 1994-97 NA. A 1990-93 1.6 car has a smaller 6-inch rear, so the later differential, driveshaft and axles must all be swapped together (the driveshaft is shorter and uses a different flange). Both sources agree. Verdict: Fits with extra parts or work. Years: 1994-1997. Applies to: 1994-97 1.8; 1990-93 only as a full set. Confidence: Confirmed (3/3). Added 2026-10-19, updated 2026-10-19, sources last read 2026-10-15. Sources: Redline Auto Parts (used-parts dealer; hands-on checks, own disclaimer) ; Randy Stocker / SoloMiata (fixjunk.com) #### Will 1994-2005 flywheel with matching clutch disc and pressure plate fit a Mazda Miata NA (1990-1997)? URL: https://chassisdex.com/mazda-miata/na/will-nb-flywheel-clutch-fit/ Answer: Yes, with extra parts or work. Direct fit on a 1994-97 1.8. The 1.6 and 1.8 flywheel/clutch parts are not interchangeable one at a time, but the whole assembly (flywheel + disc + pressure plate from a 1994-05) fits a 1990-93 car. Verdict: Fits with extra parts or work. Years: 1990-1997. Applies to: 1994-97 direct; 1990-93 as a matched set. Confidence: Confirmed (3/3). Added 2026-10-19, updated 2026-10-19, sources last read 2026-10-15. Sources: Redline Auto Parts (used-parts dealer; hands-on checks, own disclaimer) ; Randy Stocker / SoloMiata (fixjunk.com) #### Will 1999-2000 (and base 2001-02) front calipers, brackets and rotors fit a Mazda Miata NA (1990-1997)? URL: https://chassisdex.com/mazda-miata/na/will-nb-front-brakes-fit/ Answer: Yes, with extra parts or work. Reported as a direct fit on 1994-97 cars and a popular upgrade for 1990-93 cars when you also use the matching brackets, larger rotors and pads; dust shields must be modified for the larger rotors. Source is a used-parts dealer's hands-on guide, not Mazda. Not manufacturer verified. Verdict: Fits with extra parts or work. Years: 1990-1997. Applies to: direct on 1994-97; 1990-93 with brackets, rotors, pads. Confidence: Reported (2/3); safety-critical. Added 2026-10-19, updated 2026-10-19, sources last read 2026-10-15. Sources: Redline Auto Parts (used-parts dealer; hands-on checks, own disclaimer) #### Will NB factory wheels (4x100) fit a Mazda Miata NA (1990-1997)? URL: https://chassisdex.com/mazda-miata/na/will-nb-wheels-fit/ Answer: Yes. Both NA and NB use a 4x100 bolt pattern and a used-parts dealer lists NB wheels as direct fit on any NA. Check offset, tire clearance and brake clearance for your car. Verdict: Reported to fit. Years: 1990-1997. Applies to: all. Confidence: Confirmed (3/3). Added 2026-10-19, updated 2026-10-19, sources last read 2026-10-15. Sources: Redline Auto Parts (used-parts dealer; hands-on checks, own disclaimer) ; Low Offset (updated Sep 2026) #### Will NB factory hardtop fit a Mazda Miata NA (1990-1997)? URL: https://chassisdex.com/mazda-miata/na/will-nb-hardtop-fit/ Answer: Yes, reportedly. Direct fit. If the top came from a 2003-05 NB, swap the front latches to the 1990-2002 style so they match your striker plates (early 2003 cars built before 11/1/2002 had the older latches). Verdict: Reported to fit. Years: 1990-1997. Applies to: all. Confidence: Reported (2/3). Added 2026-10-19, updated 2026-10-19, sources last read 2026-10-15. Sources: Redline Auto Parts (used-parts dealer; hands-on checks, own disclaimer) #### Will NB convertible top frame / soft top assembly fit a Mazda Miata NA (1990-1997)? URL: https://chassisdex.com/mazda-miata/na/will-nb-softtop-frame-fit/ Answer: Yes, reportedly. The NB frame is a direct fit; use new tension cables. A glass-window NB soft top is direct fit on a car without a roll bar; check roll-bar compatibility if you have an aftermarket bar. Verdict: Reported to fit. Years: 1990-1997. Applies to: all (no roll bar for glass-window soft top). Confidence: Reported (2/3). Added 2026-10-19, updated 2026-10-19, sources last read 2026-10-15. Sources: Redline Auto Parts (used-parts dealer; hands-on checks, own disclaimer) #### Will NB-era sway bars (with NB brackets and bushings) fit a Mazda Miata NA (1990-1997)? URL: https://chassisdex.com/mazda-miata/na/will-nb-sway-bars-fit/ Answer: Yes, with extra parts or work. Reported to fit with aftermarket end links, plus the matching NB bar brackets and bushings. Single dealer source; suspension part, not manufacturer verified. Verdict: Fits with extra parts or work. Years: 1990-1997. Applies to: all. Confidence: Reported (2/3); safety-critical. Added 2026-10-19, updated 2026-10-19, sources last read 2026-10-15. Sources: Redline Auto Parts (used-parts dealer; hands-on checks, own disclaimer) #### Will NB complete shock/spring assemblies fit a Mazda Miata NA (1990-1997)? URL: https://chassisdex.com/mazda-miata/na/will-nb-shock-spring-fit/ Answer: Yes, with extra parts or work. Complete NB shock/spring assemblies reportedly bolt on but raise ride height; NB shocks and springs are not compatible with the NA's individually. Single dealer source; not manufacturer verified. Verdict: Fits with extra parts or work. Years: 1990-1997. Applies to: complete assemblies only. Confidence: Reported (2/3); safety-critical. Added 2026-10-19, updated 2026-10-19, sources last read 2026-10-15. Sources: Redline Auto Parts (used-parts dealer; hands-on checks, own disclaimer) #### Will 1999-2000 (NB1) ignition coil pack fit a Mazda Miata NA (1990-1997)? URL: https://chassisdex.com/mazda-miata/na/will-nb1-coilpack-fit/ Answer: Yes, reportedly. The 1999-2000 coil pack is listed as compatible with 1996-97 NA only; 2001-05 coils are listed as not compatible. Verdict: Reported to fit. Years: 1996-1997. Applies to: 1996-97 only. Confidence: Reported (2/3). Added 2026-10-19, updated 2026-10-19, sources last read 2026-10-15. Sources: Redline Auto Parts (used-parts dealer; hands-on checks, own disclaimer) #### Will NB2 (2001-05) VVT 1.8L engine fit a Mazda Miata NA (1990-1997)? URL: https://chassisdex.com/mazda-miata/na/will-nb2-vvt-engine-fit/ Answer: Yes, with extra parts or work. The dealer guide says an NB2 VVT engine can go into a 1994-97 car, reusing several NA parts and needing NB radiator hoses and throttle cable; an aftermarket ECU is recommended to run the VVT. On 1990-93 cars a Flyin' Miata swap kit is needed. Many parts (intake manifold, ECU, MAF, 2001-05 coils) are not interchangeable. The 1.6 shortblock does not take NB parts. Verdict: Fits with extra parts or work. Years: 1994-1997. Applies to: 1994-97 1.8 (1990-93: swap kit). Confidence: Reported (2/3). Added 2026-10-19, updated 2026-10-19, sources last read 2026-10-15. Sources: Redline Auto Parts (used-parts dealer; hands-on checks, own disclaimer) #### Will NB radiator fit a Mazda Miata NA (1990-1997)? URL: https://chassisdex.com/mazda-miata/na/will-nb-radiator-fit/ Answer: No. Listed as not compatible because of different mounting styles. Verdict: Does not fit. Years: 1990-1997. Applies to: all. Confidence: Reported (2/3). Added 2026-10-19, updated 2026-10-19, sources last read 2026-10-15. Sources: Redline Auto Parts (used-parts dealer; hands-on checks, own disclaimer) #### Will NB seats (on NB seat rails) fit a Mazda Miata NA (1990-1997)? URL: https://chassisdex.com/mazda-miata/na/will-nb-seats-fit/ Answer: Yes, with extra parts or work. NB seats fit with NB seat rails. On 1990-93 cars the body-mounted seatbelt buckles do not work properly with NB seat-mounted buckles, so the dealer says to remove the seat buckles or install 1994-2000 belts. Seat belts are safety equipment; get professional advice. Verdict: Fits with extra parts or work. Years: 1990-1997. Applies to: 1994-97 direct; 1990-93 belt issue. Confidence: Reported (2/3); safety-critical. Added 2026-10-19, updated 2026-10-19, sources last read 2026-10-15. Sources: Redline Auto Parts (used-parts dealer; hands-on checks, own disclaimer) #### Will 15x7 +38 wheel with 205/50R15 tire fit a Mazda Miata NA (1990-1997)? URL: https://chassisdex.com/mazda-miata/na/will-wheel-15x7-38-fit/ Answer: Yes, reportedly. One track-driving site says 15x7 +38 with 205/50-15 fits any NA or NB with no modifications. Another guide recommends +38 to +45 offsets for NA/NB 15-16 inch wheels. Lowered cars or extra camber may change this. Verdict: Reported to fit. Years: 1990-1997. Applies to: stock-height. Confidence: Reported (2/3). Added 2026-10-19, updated 2026-10-19, sources last read 2026-10-15. Sources: Race & Track Driving (Mar 2018) ; Low Offset (updated Sep 2026) #### Will 15x9 +36 wheel with 225/45R15 tire fit a Mazda Miata NA (1990-1997)? URL: https://chassisdex.com/mazda-miata/na/will-wheel-15x9-36-fit/ Answer: Yes, with extra parts or work. 15x9 +36 with 225/45-15: all inside fender edges flat-rolled, a light pull on the front fenders, and about -3 degrees front camber for full clearance; wider tires (Hoosiers, 245/40) need a moderate pull. Based on one driver's experience. Verdict: Fits with extra parts or work. Years: 1990-1997. Applies to: needs fender work. Confidence: Reported (2/3). Added 2026-10-19, updated 2026-10-19, sources last read 2026-10-15. Sources: Race & Track Driving (Mar 2018) #### Will Tein Street Basis Z coilovers fit a Mazda Miata NA (1990-1997)? URL: https://chassisdex.com/mazda-miata/na/will-tein-street-basis-z-fit/ Answer: Yes, reportedly. One editorial roundup lists this coilover as an NA/NB option. No vendor fitment table was checked; confirm with Tein's own application chart. Suspension is safety-critical. Verdict: Reported to fit. Years: 1990-1997. Applies to: model-specific listing. Confidence: Limited (1/3); safety-critical. Added 2026-10-19, updated 2026-10-19, sources last read 2026-10-15. Sources: Low Offset (updated Sep 2026) #### What is the factory spec for the OEM NA wheel (14x5.5 or 15x6, +45) on a Mazda Miata NA (1990-1997)? URL: https://chassisdex.com/mazda-miata/na/will-oem-na-wheel-fit/ Answer: Factory specification. A modifications guide gives NA stock wheels as 14x5.5 or 15x6, +45 offset, 4x100 PCD (single source; the bolt pattern is confirmed by a second source). Verdict: Specification. Years: 1990-1997. Applies to: all. Confidence: Reported (2/3). Added 2026-10-19, updated 2026-10-19, sources last read 2026-10-15. Sources: Low Offset (updated Sep 2026) ; Redline Auto Parts (used-parts dealer; hands-on checks, own disclaimer) #### Will 15x8 +25 wheel (4x100) with 205/50R15 tire fit a Mazda Miata NA (1990-1997)? URL: https://chassisdex.com/mazda-miata/na/will-wheel-15x8-25-fit/ Answer: Yes, with extra parts or work. Two wheel guides agree 15x8 +25 with a 205/50R15 is a popular NA setup that sits close to flush, and that a mild fender roll may be needed depending on ride height and camber (one suggests about -1.5 degrees). A 225/45R15 on the same wheel needs more fender work. NA owners on a forum report front tire contact over bumps until the front lips were rolled flat. The vendor's 15x8 +25 clears factory NA/NB brakes; aftermarket 4x100 wheels often have a 67.1mm bore, so centering rings are optional on the 54.1mm Miata hub. Verdict: Fits with extra parts or work. Years: 1990-1997. Applies to: 205/50R15; fender roll depends on ride height, alignment and tire. Confidence: Confirmed (3/3). Added 2026-10-21, updated 2026-10-21, sources last read 2026-10-21. Sources: rimlist (wheel listings and guides; contains affiliate links) ; Flyin' Miata (Miata parts vendor) ; MX-5 Miata Forum #### Will NC Miata (2006-2015) factory or NC-fitment wheels fit a Mazda Miata NA (1990-1997)? URL: https://chassisdex.com/mazda-miata/na/will-nc-miata-wheels-fit/ Answer: No. NC Miata wheels use a 5x114.3 five-lug pattern (67.1mm bore per one wheel maker), while every NA uses 4x100, so they do not bolt on. Several sources agree on the pattern split; adapters are not recommended by the guides we read. Shop for 4x100 wheels instead. Verdict: Does not fit. Years: 1990-1997. Applies to: all NA. Confidence: Confirmed (3/3). Added 2026-10-21, updated 2026-10-21, sources last read 2026-10-21. Sources: Grip Theory (wheel maker) ; Miata.net FAQ ; MX-5 Owners Club (UK) forum #### Will ND Miata (2016+) factory wheels (4x100, 16x6.5 or 17x7 +45) fit a Mazda Miata NA (1990-1997)? URL: https://chassisdex.com/mazda-miata/na/will-nd-miata-wheels-fit/ Answer: Yes, reportedly. ND wheels share the NA's 4x100 bolt pattern and +45 offset (Miata.net's wheel table lists both), and their 54.1 mm bore matches the Miata hub, so they bolt on. A Miata parts-vendor staffer on the Grassroots Motorsports forum says they have fitted ND wheels to an NA/NB and it works, but looks awkward: the offset is high and the ND tire is tall. By our arithmetic a 205/45R17 is about 7% taller than the NA's 185/60R14 (and a 195/50R16 about 4% taller), so the speedometer will read low unless you fit a lower-profile tire. ND wheels are sized to clear ND brakes, so stock NA brakes are not the problem; check spoke clearance with any aftermarket big brake kit. Verdict: Reported to fit. Years: 1990-1997. Applies to: all NA. Confidence: Reported (2/3). Added 2026-10-22, updated 2026-10-22, sources last read 2026-10-22. Sources: Miata.net FAQ ; Miatafy (enthusiast guide site) ; Grassroots Motorsports forum (2016; includes a reply from a Miata parts-vendor staffer) #### Will Aftermarket (non-Mazda) NA/NB hardtop fit a Mazda Miata NA (1990-1997)? URL: https://chassisdex.com/mazda-miata/na/will-aftermarket-hardtop-fit/ Answer: Yes, reportedly. The Miata.net hardtop FAQ says aftermarket (non-Mazda) tops should fit all NA and NB cars, and that most use the old-style front latches and NA-style defroster plug, which suits an NA. Quality is the issue rather than fit: the FAQ reports mixed to poor owner feedback on several aftermarket tops and says most people recommend a used Mazda top because aftermarket ones are not much cheaper. Lightweight fiberglass race tops often ship as a bare shell with the window, brackets and seals as extras. Treat as a lead and check exactly what hardware is included. Verdict: Reported to fit. Years: 1990-1997. Applies to: all NA. Confidence: Limited (1/3). Added 2026-10-22, updated 2026-10-22, sources last read 2026-10-22. Sources: Miata.net Garage ; MX5Global (enthusiast guide site, Oct 2026) #### Will 15x8 +28 wheel (4x100), e.g. Enkei RPF1, with 205/50R15 fit a Mazda Miata NA (1990-1997)? URL: https://chassisdex.com/mazda-miata/na/will-wheel-15x8-28-fit/ Answer: Yes, reportedly. A 15x8 +28 (the Enkei RPF1 size) is the slightly more conservative cousin of the popular 15x8 +25: it sits 3 mm further inboard. A wheel guide lists it for 205/50R15 or 225/45R15 on an NA and says it may avoid fender rolling at stock height, with about -1.5 degrees of camber and a roll recommended once lowered. On a turbo-Miata forum the founder of a Miata wheel company says it is fine on stock shocks, while an NA owner calls it tight on an NA and says even a light lip roll helps a lot; his 225s rub on big bumps. Reddit replies are split on whether an unrolled 1990 car needs a roll. Bump travel, not static ride height, decides rubbing, so coilovers that allow more compression make contact more likely. Not every 205/50 is the same width; a parts vendor notes 200-treadwear tires suit an 8-inch rim better than all-seasons. Verdict: Reported to fit. Years: 1990-1997. Applies to: 205/50R15; stock suspension or mild drop; roll the fender lips if lowered or on coilovers. Confidence: Reported (2/3). Added 2026-10-23, updated 2026-10-23, sources last read 2026-10-23. Sources: rimlist (wheel listings and guides; contains affiliate links) ; Miata Turbo Forum (2023-24; includes a reply from the founder of 949 Racing) ; r/Miata (2025 owner replies, mixed) ; MX-5 Miata Forum (includes a reply from Good-Win Racing, a Miata parts vendor) #### Will 15x8 +34 to +36 wheel (4x100), e.g. 949 Racing 6UL fit a Mazda Miata NA (1990-1997)? URL: https://chassisdex.com/mazda-miata/na/will-wheel-15x8-36-fit/ Answer: Yes, reportedly. The higher-offset 15x8 sits further inboard than a +25/+28, which makes it one of the easier wide wheels to fit on an NA. The 6UL's original 15x8 was +36; the 2026 Gen6 version is +34, so check which you are buying. An old SuperMiata fitment table (quoted on a turbo-Miata forum) says 195/45 through 225/45 tires fit with standard-length dampers without rubbing; 225/45 may need the liner trimmed with short-body coilovers that allow more bump travel, 225/50 needs liner trimming and a fender roll on an NA, and at least -1.25 degrees of front camber is suggested for 225/45 on an NA. A UK owner calls 15x8 +36 about the biggest an NA takes 'without surgery'. The maker says the Gen6 wheel clears NB Sport brakes and its own 11-inch big brake kit. Verdict: Reported to fit. Years: 1990-1997. Applies to: 205/50R15 or 225/45R15 on standard-length dampers; 225/50 needs liner trim and a roll. Confidence: Reported (2/3). Added 2026-10-23, updated 2026-10-23, sources last read 2026-10-23. Sources: Miata Turbo Forum (2018) ; 949 Racing (wheel maker) ; ClubRoadster.net (thread started by the 6UL's designer) ### NA known problems #### Short-nose crankshaft (1990 and early 1991) (1990-early 1991 (1.6L)) URL: https://chassisdex.com/mazda-miata/na/problems/short-nose-crankshaft/ Severity: High. Confidence: Confirmed. Updated 2026-10-19. Symptoms: Crank pulley wobble; bolt failure; ultimately crankshaft replacement. Cause: The early 1.6 timing-belt job included the crank seal, and improper reassembly of the pulley key can lead to the bolt failing. Hagerty says it affected about 1% of those cars; Mazda changed the crank nose partway through 1991. Fix: Have a timing belt done by someone who knows the early engine; the crank seal is now usually skipped unless leaking. When buying, look for crank-pulley wobble. Sources: Hagerty Media (Mar 2021) ; Miata.net ; miatayear.com ; Redline Auto Parts (used-parts dealer; hands-on checks, own disclaimer) #### Rocker and floor rust from clogged drains (1990-1997) URL: https://chassisdex.com/mazda-miata/na/problems/rust-and-clogged-drains/ Severity: Medium. Confidence: Reported. Updated 2026-10-19. Symptoms: Smelly or wet carpets, rusty rockers (notably ahead of the rear wheel arches), blown-out floors. Cause: Hagerty says the body drains plug up quickly, letting water back up inside. Fix: Clear the drains, inspect the rockers and floors, and have a body shop repair rust. Sources: Hagerty Media (Mar 2021) #### 1990-93 1.6 uses a smaller 6-inch rear differential (1990-1993) URL: https://chassisdex.com/mazda-miata/na/problems/weaker-1-6-differential/ Severity: Low. Confidence: Reported. Updated 2026-10-19. Symptoms: Not a reported failure on its own. It limits parts swaps and is described as not very strong. Cause: The 1.6's rear end derives from an older design with a 6-inch ring gear; 1994 brought a larger 7-inch unit. Fix: Moving to the 94+ differential requires the matching housing, driveshaft and axles. Sources: Randy Stocker / SoloMiata (fixjunk.com) ; Redline Auto Parts (used-parts dealer; hands-on checks, own disclaimer) #### Cooling parts crack with age and heat (1990-1997 (and NB)) URL: https://chassisdex.com/mazda-miata/na/problems/cooling-hoses-reservoir-cracking/ Severity: Medium. Confidence: Limited. Updated 2026-10-19. Symptoms: Coolant leaks from the reservoir and hoses, especially in hot dry climates. Cause: A year-by-year problem list says reservoirs and hoses crack in hot, dry climates (search excerpt only; page could not be fully read). Fix: Replace aged hoses and reservoir proactively. Sources: miatayear.com #### Verify timing belt and plug service history (1990-1997) URL: https://chassisdex.com/mazda-miata/na/problems/timing-belt-history/ Severity: Medium. Confidence: Limited. Updated 2026-10-19. Symptoms: No symptom until failure. Cause: Miata.net's used-car checklist tells buyers to ask about timing belt and spark-plug service history. The exact interval it lists was not captured, so check Mazda's schedule. Fix: Ask for records or budget for the service, using the correct procedure on short-nose cars. Sources: Miata.net ; Hagerty Media (Mar 2021) #### Oil leaks from the CAS O-ring and valve cover gasket (1990-1997 (all NA)) URL: https://chassisdex.com/mazda-miata/na/problems/cas-o-ring-valve-cover-oil-leaks/ Severity: Low. Confidence: Confirmed. Updated 2026-10-22. Symptoms: Drops of oil under the back of the engine, oil on the firewall or bellhousing, a burning-oil smell, or oil in the spark plug wells. Cause: The cam angle sensor (CAS) at the back of the valve cover seals with an O-ring that commonly hardens and leaks; the valve cover gasket is the other usual suspect. Oil from a CAS leak can drip onto the heater hose below it and rot it, turning an oil leak into a coolant leak. A DIY guide and forum owners agree these, plus the front main seal, are the classic old-Miata leaks. Fix: Degrease the engine, drive, then look for fresh oil to find the source. Both are cheap DIY jobs: mark the CAS position before removing it (one 12mm bolt) so ignition timing stays put, fit a new O-ring, and many owners replace the valve cover gasket at the same time. Check the heater hose under the CAS while you are there. The front main and cam seals are easiest to do with the timing belt. Sources: Miata.Repair (DIY guide site) ; MX-5 Miata Forum ; MX-5 Miata Forum ; Miata.Repair (DIY guide site) #### Soft-top water leaks: blocked drains, cracked rain rail, side windows and zipper (1990-1997 (soft-top cars; same layout as the NB)) URL: https://chassisdex.com/mazda-miata/na/problems/soft-top-water-leaks/ Severity: Medium. Confidence: Reported. Updated 2026-10-23. Symptoms: Water on the rear parcel shelf or behind the seats, damp or moldy carpet, water sloshing in the sills, drips at the front corners of the top or past the side-window seals. Cause: The soft top is not sealed. Water running off it collects in a plastic rain rail along the base of the top and empties through a drain on each side, in the corner between the seatbelt tower and the body. When those drains clog, water overflows onto the shelf, and owners warn that moldy carpet usually means rusting metal underneath. On older cars the rain rail itself cracks and leaks onto the shelf near the rear window (replacement rails for 1990-2005 are sold). Side-window and windshield-header leaks come from shifted or dirty weatherstrips and latches that no longer pull the top down tight. Fix: Clear both drains first: tilt the seats forward, unlatch the top and fold back the carpet flap behind each seatbelt tower, then feed something soft and flexible down the tube (a club article warns against damaging the flap valve at the bottom) and test with water. If water still reaches the shelf near the rear window, check the rain rail for cracks and replace it. For side-window drips, owners suggest closing the door after raising the window so the glass seats differently, and a little petroleum jelly where the rubber meets the glass; adjust or replace tired weatherstrips and latches. See the NA rust and drains entry for what trapped water does to the sills. Sources: MX-5 Club of Victoria (club magazine tech article, 2012) ; MX-5 Miata Forum ; Moss Miata (parts retailer) ; Buckeye Miata Club (club newsletter, 2006) ### NA build entries by goal #### First steps: Start with tires, brake pads and driving time URL: https://chassisdex.com/mazda-miata/na/best-mods/first-steps/#tires-pads-and-track-days-first Road & Track's advice for NBs: buy good tires and pads and spend the suspension budget on track days first; a roly-poly stock Miata helps you learn weight transfer. Caveats: Opinion from one editorial. Confidence: Reported. Updated 2026-10-19. Sources: Road & Track (Jun 2016) #### Suspension: Coilovers, sway bars and strut-tower brace URL: https://chassisdex.com/mazda-miata/na/best-mods/suspension/#coilovers-sway-bars-and-braces A mod guide ranks coilovers as a top bang-for-buck suspension mod, lists many NA/NB-compatible kits, and says sway bars and a front tower bar tighten handling. Caveats: Listings are from one editorial roundup and were not checked against vendor charts. Safety-critical. Confidence: Limited. Updated 2026-10-19. Sources: Low Offset (updated Sep 2026) #### Wheels & tires: 15x7 +38 wheel and 205/50R15 tire URL: https://chassisdex.com/mazda-miata/na/best-mods/wheels-tires/#15x7-wheel-and-tire 15x7 is called the standard Spec Miata wheel size; +38 205/50-15 is reported to fit any NA/NB with no modifications. Caveats: Single source for the specific fit; lowered or heavily cambered cars may rub. Confidence: Reported. Updated 2026-10-19. Sources: Race & Track Driving (Mar 2018) ; Low Offset (updated Sep 2026) #### Drivetrain: NB 6-speed into an NA URL: https://chassisdex.com/mazda-miata/na/best-mods/drivetrain/#nb-6-speed-swap Two sources agree a 6-speed bolts in with shifter/plate changes; gearing needs attention. Caveats: See the fitment page for starter, speedometer and rear-gear notes. Confidence: Confirmed. Updated 2026-10-19. Sources: Randy Stocker / SoloMiata (fixjunk.com) ; Redline Auto Parts (used-parts dealer; hands-on checks, own disclaimer) #### Drivetrain: Limited-slip differential URL: https://chassisdex.com/mazda-miata/na/best-mods/drivetrain/#limited-slip-differential Hagerty says any NA is one phone call away from having a limited slip; Road & Track says NBs from 2003 use a Tochigi-Fugi LSD instead of the Torsen and that both beat an open differential. Caveats: Check what your car already has: NA 1990-93 viscous option; Torsen optional from 1994. Confidence: Reported. Updated 2026-10-19. Sources: Hagerty Media (Mar 2021) ; Road & Track (Jun 2016) #### Brakes: Larger NB brakes on a 1990-93 NA URL: https://chassisdex.com/mazda-miata/na/best-mods/brakes/#nb-brakes-on-early-na A used-parts dealer calls the NB/1994+ front brake combination a popular upgrade for 1990-93 cars; dust shields need modification. Caveats: Safety-critical; dealer source only, not Mazda. Confidence: Reported. Updated 2026-10-19. Sources: Redline Auto Parts (used-parts dealer; hands-on checks, own disclaimer) #### Power: Forced induction and engine swaps URL: https://chassisdex.com/mazda-miata/na/best-mods/power/#forced-induction-and-swaps R&T and a mod guide say turbo and supercharger kits are common; the Mazdaspeed's non-VVT head and lower redline limit big power; buying someone else's finished build is cheaper; and the clutch needs upgrading at higher power. Caveats: No kit is recommended here; no power figures are verified. Confidence: Reported. Updated 2026-10-19. Sources: Road & Track (Jun 2016) ; Low Offset (updated Sep 2026) ## Mazda Miata NB (1999-2005 US model years) URL: https://chassisdex.com/mazda-miata/nb/ Years: 1999-2005 (US model years; NB debuted in 1998 as a 1999 model). Trims: Base, sport package, special editions, 2004-05 Mazdaspeed (turbo, ~178 hp). 6-speed was special-edition/option in 1999-2000 and became a regular option for 2001. Engine: 1.8L; NB1 (1999-2000) and NB2 (2001-2005, with variable valve timing). Mazdaspeed 2004-05: turbo, non-VVT head. Notes: NB1 and NB2 differ in ignition (NB1 coil packs vs different NB2 system) and other details. Last two years: 16-inch wheels standard and 6-speed rear gearing 3.90 instead of 4.10 (per Road & Track). Sources: https://www.roadandtrack.com/car-culture/a29765/nb-mazda-miata-buyers-guide/ ; https://forum.miata.net/vb/showthread.php?t=552185 ### NB fitment answers #### What is the factory spec for the OEM NB wheel (14x6 or 15x6, +40) on a Mazda Miata NB (1999-2005 US model years)? URL: https://chassisdex.com/mazda-miata/nb/will-oem-nb-wheel-fit/ Answer: Factory specification. Stock NB wheels listed as 14x6 or 15x6, +40 offset, 4x100. Road & Track notes 16-inch wheels became standard in the last two production years. Correction note (2026-10-23): a wheel guide gives a fuller trim table: 14x6 +45 on 1999-2000 base/LS, 15x6 +40 on 1999-2000 Sport and 2001-03 base/LS, 16x6.5 +40 on 2001-03 Sport/SE and all 2004-05, and 17x7 +40 on the Mazdaspeed MX-5. Sources disagree on the 14-inch offset (+40 vs +45); check the stamp on the wheel. Verdict: Specification. Years: 1999-2005. Applies to: all. Confidence: Reported (2/3). Added 2026-10-19, updated 2026-10-23, sources last read 2026-10-23. Sources: Low Offset (updated Sep 2026) ; Road & Track (Jun 2016) ; rimlist (wheel listings and guides; contains affiliate links) #### Will 15x7 +38 wheel with 205/50R15 tire fit a Mazda Miata NB (1999-2005 US model years)? URL: https://chassisdex.com/mazda-miata/nb/will-wheel-15x7-38-fit/ Answer: Yes, reportedly. 15x7 +38 with 205/50-15 is reported to fit with no modifications (same source as the NA entry). Verdict: Reported to fit. Years: 1999-2005. Applies to: stock-height. Confidence: Reported (2/3). Added 2026-10-19, updated 2026-10-19, sources last read 2026-10-15. Sources: Race & Track Driving (Mar 2018) #### Will 15x9 +36 wheel with 225/45R15 tire fit a Mazda Miata NB (1999-2005 US model years)? URL: https://chassisdex.com/mazda-miata/nb/will-wheel-15x9-36-fit/ Answer: Yes, with extra parts or work. On an NB with 225/45-15 this is reported to fit with a flat fender roll, even on stock suspension at stock alignment; the stock springs may lightly rub at full steering lock. Wider tires need a light front pull and camber. Verdict: Fits with extra parts or work. Years: 1999-2005. Applies to: flat roll. Confidence: Reported (2/3). Added 2026-10-19, updated 2026-10-19, sources last read 2026-10-15. Sources: Race & Track Driving (Mar 2018) #### Will Tein Street Basis Z coilovers fit a Mazda Miata NB (1999-2005 US model years)? URL: https://chassisdex.com/mazda-miata/nb/will-tein-street-basis-z-fit/ Answer: Yes, reportedly. Same single editorial roundup lists it for NA/NB. Verify against Tein's application chart. Suspension is safety-critical. Verdict: Reported to fit. Years: 1999-2005. Applies to: model-specific listing. Confidence: Limited (1/3); safety-critical. Added 2026-10-19, updated 2026-10-19, sources last read 2026-10-15. Sources: Low Offset (updated Sep 2026) #### Will NB2 "Sport" brake package (2001-02 LS/SE, all 2003-05) fit a Mazda Miata NB (1999-2005 US model years)? URL: https://chassisdex.com/mazda-miata/nb/will-nb2-sport-brakes-fit/ Answer: Yes, with extra parts or work. A used-parts dealer says the Sport package fits an NB1 if you move over the calipers, larger caliper brackets, rotors, pads and front brake lines, and trim the dust shields; factory 14-inch wheels and some 15-inch wheels will not clear. A forum owner who did the swap adds that the Sport calipers take more fluid, so expect a longer pedal unless the master cylinder (and with it the booster) is changed too. Not manufacturer verified. Verdict: Fits with extra parts or work. Years: 1999-2000. Applies to: NB1 (1999-2000); 2001-02 base cars already have the smaller brakes. Confidence: Reported (2/3); safety-critical. Added 2026-10-20, updated 2026-10-20, sources last read 2026-10-20. Sources: Redline Auto Parts (used-parts dealer; hands-on checks, own disclaimer; Dec 2018) ; MX-5 Miata Forum ; Mazda North American Operations (press spec sheet) #### Will NB2 (2001-05) VVT 1.8L engine fit a Mazda Miata NB (1999-2005 US model years)? URL: https://chassisdex.com/mazda-miata/nb/will-nb2-vvt-engine-fit/ Answer: Yes, with extra parts or work. Reported to go in with wiring work: keep the NB1 accessories, throttle body and engine harness, add the NB2 coil connectors and move the cam-sensor plug to the back of the head. The NB2 ECU does not fit (immobilizer and different wiring), so the VVT solenoid can be left unplugged to run fixed timing, or an aftermarket ECU / VVT controller used to get the benefit. Single dealer source. Verdict: Fits with extra parts or work. Years: 1999-2000. Applies to: NB1 (1999-2000). Confidence: Reported (2/3). Added 2026-10-20, updated 2026-10-20, sources last read 2026-10-20. Sources: Redline Auto Parts (used-parts dealer; hands-on checks, own disclaimer; Dec 2018) #### Will NB 6-speed manual transmission (with NB shifter) fit a Mazda Miata NB (1999-2005 US model years)? URL: https://chassisdex.com/mazda-miata/nb/will-nb-6speed-trans-fit/ Answer: Yes. Sources agree the 6-speed bolts into a 5-speed NB. A forum poster found the NB 5-speed and 6-speed transmission plates identical and the starter used all three bolts (the two-bolt starter issue applies to NA cars). Use the shifter from the same car: one dealer says only early-2001 6-speed shifters match the NB1 unit; mid-2001-on cars use a larger shifter. Reverse/neutral switch wiring may need attention on swaps. Match the rear ratio (6-speed cars used 3.909, 2004-05 cars 4.10). Verdict: Reported to fit. Years: 1999-2005. Applies to: manual NB; bring the shifter from the donor car. Confidence: Confirmed (3/3). Added 2026-10-20, updated 2026-10-20, sources last read 2026-10-20. Sources: Redline Auto Parts (used-parts dealer; hands-on checks, own disclaimer; Dec 2018) ; Miata Turbo Forum ; MiataSource (parts vendor blog) #### Will 2004-05 Mazdaspeed Miata Torsen differential with MSM axles fit a Mazda Miata NB (1999-2005 US model years)? URL: https://chassisdex.com/mazda-miata/nb/will-msm-torsen-axles-fit/ Answer: Yes, with extra parts or work. Two dealer guides agree the Mazdaspeed rear uses a larger Torsen unit and larger-diameter axles; it fits any 1999-2005 NB when the MSM axles come with it, and the MSM axles only work with the MSM differential. A forum poster also notes the MSM's inner axle shafts are larger. Final drive is 4.10. Verdict: Fits with extra parts or work. Years: 1999-2005. Applies to: only as a set: MSM differential + MSM axles. Confidence: Confirmed (3/3). Added 2026-10-20, updated 2026-10-20, sources last read 2026-10-20. Sources: Redline Auto Parts (used-parts dealer; hands-on checks, own disclaimer; Dec 2018) ; Redline Auto Parts (used-parts dealer) ; MX-5 Miata Forum #### Will 1994-2005 differential, driveshaft and axles (7-inch rear) fit a Mazda Miata NB (1999-2005 US model years)? URL: https://chassisdex.com/mazda-miata/nb/will-nb-diff-driveshaft-axles-fit/ Answer: Yes. 1994-2005 1.8 rear ends (open or Torsen/LSD) interchange on an NB without changing axles or driveshaft, except Mazdaspeed units. Watch the ratio: NA8 4.1, NB 5-speed 4.3, US 6-speed 3.909, 2004-05 6-speed 4.10. Swapping only the LSD 'pumpkin' into your housing needs resealing; swapping a complete rear is simpler. Verdict: Reported to fit. Years: 1999-2005. Applies to: non-Mazdaspeed 1.8 rear ends. Confidence: Confirmed (3/3). Added 2026-10-20, updated 2026-10-20, sources last read 2026-10-20. Sources: MX-5 Miata Forum ; MX-5 Miata Forum ; Redline Auto Parts (used-parts dealer) #### Will NB2 (2001-05) tubular exhaust manifold with EGR tube fit a Mazda Miata NB (1999-2005 US model years)? URL: https://chassisdex.com/mazda-miata/nb/will-nb2-exhaust-manifold-fit/ Answer: Yes, with extra parts or work. Described as a popular NB1 upgrade. Federal cars need the manifold plus the NB2 EGR tube (heat shields optional). California-emissions cars also need extended O2 sensor wiring and an extra sensor bung after the mid-pipe converter. Single dealer source. Verdict: Fits with extra parts or work. Years: 1999-2000. Applies to: NB1; California-emissions cars need more parts. Confidence: Reported (2/3). Added 2026-10-20, updated 2026-10-20, sources last read 2026-10-20. Sources: Redline Auto Parts (used-parts dealer; hands-on checks, own disclaimer; Dec 2018) #### Will Mazdaspeed Miata BP5A intake camshaft fit a Mazda Miata NB (1999-2005 US model years)? URL: https://chassisdex.com/mazda-miata/nb/will-msm-bp5a-intake-cam-fit/ Answer: Yes, reportedly. The Mazdaspeed's more aggressive BP5A intake cam is described as a direct-fit upgrade for a 1999-2000 engine. It does not fit the 2001-05 VVT engine. Single dealer source; check cam timing setup with a shop manual. Verdict: Reported to fit. Years: 1999-2000. Applies to: NB1 non-VVT engines only; does NOT fit 2001-05 VVT. Confidence: Reported (2/3). Added 2026-10-20, updated 2026-10-20, sources last read 2026-10-20. Sources: Redline Auto Parts (used-parts dealer; hands-on checks, own disclaimer; Dec 2018) #### Will Mazdaspeed Miata sway bars (with MSM bushings and brackets) fit a Mazda Miata NB (1999-2005 US model years)? URL: https://chassisdex.com/mazda-miata/nb/will-msm-sway-bars-fit/ Answer: Yes, with extra parts or work. Reported to fit any 1999-2005 NB if you also use the Mazdaspeed bar bushings and mounting brackets. Mazda's spec sheet confirms the Mazdaspeed has larger bars than other Miatas but says nothing about fitting them to other cars. Suspension part; not manufacturer verified. Verdict: Fits with extra parts or work. Years: 1999-2005. Applies to: use MSM bushings and brackets. Confidence: Reported (2/3); safety-critical. Added 2026-10-20, updated 2026-10-20, sources last read 2026-10-20. Sources: Redline Auto Parts (used-parts dealer; hands-on checks, own disclaimer; Dec 2018) ; Mazda North American Operations (press spec sheet) #### Will Mazdaspeed Miata 17x7 wheels fit a Mazda Miata NB (1999-2005 US model years)? URL: https://chassisdex.com/mazda-miata/nb/will-msm-wheels-17x7-fit/ Answer: Yes, reportedly. Listed as a direct fit on any 1999-2005 NB. Mazda's spec sheet gives the factory size as 17x7 with 205/40R17 tires. Check tire clearance if the car is lowered. Verdict: Reported to fit. Years: 1999-2005. Applies to: all NB. Confidence: Reported (2/3). Added 2026-10-20, updated 2026-10-20, sources last read 2026-10-20. Sources: Redline Auto Parts (used-parts dealer; hands-on checks, own disclaimer; Dec 2018) ; Mazda North American Operations (press spec sheet) #### Will NB2 / Mazdaspeed seats fit a Mazda Miata NB (1999-2005 US model years)? URL: https://chassisdex.com/mazda-miata/nb/will-nb2-seats-fit/ Answer: Yes, reportedly. NB2 seats are listed as a direct fit in an NB1, and Mazdaspeed seats as a direct fit in any 1999-2005 NB. Single dealer source. Verdict: Reported to fit. Years: 1999-2000. Applies to: NB1; Mazdaspeed seats listed for all NB. Confidence: Reported (2/3). Added 2026-10-20, updated 2026-10-20, sources last read 2026-10-20. Sources: Redline Auto Parts (used-parts dealer; hands-on checks, own disclaimer; Dec 2018) #### Will NB2 (2001-05) seatbelts with pyrotechnic pretensioners fit a Mazda Miata NB (1999-2005 US model years)? URL: https://chassisdex.com/mazda-miata/nb/will-nb2-seatbelts-fit/ Answer: No. Listed as not compatible: NB2 belts have a pyrotechnic pretensioner that the NB1 is not wired for. Restraints are safety-critical; use the belts specified for your car. Verdict: Does not fit. Years: 1999-2000. Applies to: NB1. Confidence: Reported (2/3); safety-critical. Added 2026-10-20, updated 2026-10-20, sources last read 2026-10-20. Sources: Redline Auto Parts (used-parts dealer; hands-on checks, own disclaimer; Dec 2018) #### Will NB2 (2001-05) engine computer (ECU) fit a Mazda Miata NB (1999-2005 US model years)? URL: https://chassisdex.com/mazda-miata/nb/will-nb2-ecu-fit/ Answer: No. Listed as not compatible: NB2 ECUs include an immobilizer the NB1 lacks and use different wiring. The NB2 mass airflow sensor is also a different calibration. The Mazdaspeed ECU is listed as not directly compatible with any other NB. Verdict: Does not fit. Years: 1999-2000. Applies to: NB1. Confidence: Reported (2/3). Added 2026-10-20, updated 2026-10-20, sources last read 2026-10-20. Sources: Redline Auto Parts (used-parts dealer; hands-on checks, own disclaimer; Dec 2018) #### Will NA (1990-97) factory hardtop fit a Mazda Miata NB (1999-2005 US model years)? URL: https://chassisdex.com/mazda-miata/nb/will-na-hardtop-fit/ Answer: Yes, with extra parts or work. The Miata.net hardtop FAQ and a forum thread describe an NA hardtop going onto an NB with matching side striker plates and the rear-deck hold-down bolts. The rear-defroster connector differs between generations, and cars built from late 2002 (2003 model year) use redesigned front latches, so check latch compatibility. Search excerpts only; confirm hardware before buying. Verdict: Fits with extra parts or work. Years: 1999-2005. Applies to: needs NB-style strikers/rear bolts; 2003+ latch change. Confidence: Reported (2/3). Added 2026-10-20, updated 2026-10-20, sources last read 2026-10-20. Sources: Miata.net Garage ; Grassroots Motorsports forum #### Will NB2 front bumper and headlights fit a Mazda Miata NB (1999-2005 US model years)? URL: https://chassisdex.com/mazda-miata/nb/will-nb2-front-bumper-headlights-fit/ Answer: Yes, with extra parts or work. The NB2 headlights only fit with the NB2 bumper (and vice versa). NB1 lights use one bulb for low and high beam; NB2 uses two, so the wiring has to change. NB2 fog lights do not fit an NB1 bumper and the NB2/MSM front lip only fits the 2001-05 bumper. Single dealer source. Verdict: Fits with extra parts or work. Years: 1999-2000. Applies to: NB1; bumper and headlights must be swapped together. Confidence: Reported (2/3). Added 2026-10-20, updated 2026-10-20, sources last read 2026-10-20. Sources: Redline Auto Parts (used-parts dealer; hands-on checks, own disclaimer; Dec 2018) #### Will 15x8 +25 wheel (4x100) with 205/50R15 tire fit a Mazda Miata NB (1999-2005 US model years)? URL: https://chassisdex.com/mazda-miata/nb/will-wheel-15x8-25-fit/ Answer: Yes, reportedly. A Miata vendor says NBs should take 15x8 +25 with 205/50R15 without modification in most cases, because the NB has more fender room than the NA. Forum owners mostly agree (one reports no rubbing on a 2002 at about 12 inches hub-to-fender) but at least one says a roll was still needed, so treat it as height- and tire-dependent. Verdict: Reported to fit. Years: 1999-2005. Applies to: 205/50R15; check clearance if lowered. Confidence: Reported (2/3). Added 2026-10-21, updated 2026-10-21, sources last read 2026-10-21. Sources: Flyin' Miata (Miata parts vendor) ; ClubRoadster.net #### Will NC Miata (2006-2015) factory or NC-fitment wheels fit a Mazda Miata NB (1999-2005 US model years)? URL: https://chassisdex.com/mazda-miata/nb/will-nc-miata-wheels-fit/ Answer: No. Same as the NA: the NB uses 4x100 and the NC uses 5x114.3, so NC wheels do not bolt on. (ND Miata wheels are 4x100 like NA/NB, which is why NC wheels are the odd ones out.) Verdict: Does not fit. Years: 1999-2005. Applies to: all NB. Confidence: Confirmed (3/3). Added 2026-10-21, updated 2026-10-21, sources last read 2026-10-21. Sources: Grip Theory (wheel maker) ; Miata.net FAQ ; MX-5 Owners Club (UK) forum #### Will ND Miata (2016+) factory wheels (4x100, 16x6.5 or 17x7 +45) fit a Mazda Miata NB (1999-2005 US model years)? URL: https://chassisdex.com/mazda-miata/nb/will-nd-miata-wheels-fit/ Answer: Yes, reportedly. Same story as the NA: the ND is 4x100 with a 54.1 mm bore like the NB, so its wheels bolt on. The ND's +45 offset is a little higher than the NB's factory +40, which tucks the wheel slightly further in. A Miata parts-vendor staffer says they have run ND wheels on an NA/NB and it looks awkward (high offset, tall tire). By our arithmetic a 205/45R17 is about 7% taller than the NB's 195/50R15, so use a lower-profile tire to keep the speedometer close. Brake clearance is not an issue with factory NB brakes (the ND wheel is made to clear larger ND calipers); check with big brake kits. Verdict: Reported to fit. Years: 1999-2005. Applies to: all NB. Confidence: Reported (2/3). Added 2026-10-22, updated 2026-10-22, sources last read 2026-10-22. Sources: Miata.net FAQ ; Miatafy (enthusiast guide site) ; Grassroots Motorsports forum (2016; includes a reply from a Miata parts-vendor staffer) #### Will NB factory hardtop fit a Mazda Miata NB (1999-2005 US model years)? URL: https://chassisdex.com/mazda-miata/nb/will-nb-hardtop-fit/ Answer: Yes, reportedly. An NB factory hardtop is the native roof for any NB, and all NB tops use the same defroster plug, so any NB top plugs into any NB car. The catch is the front latches: Mazda changed the front latches and windshield-header strikers on cars built from November 1, 2002 (part way through the 2003 model year). A top from a 1999 to early-2003 car needs late latches on a late car, and a late top needs early latches on an earlier car. Read the build month on the driver's door-jamb label rather than trusting the model year. Cars that never had a hardtop may also lack the side strikers and rear deck bolts. A specialist retailer and the Miata.net FAQ agree on the latch split; the FAQ was read only as a search excerpt, so this stays at tier 2. Verdict: Reported to fit. Years: 1999-2005. Applies to: all NB; front latches must match the car's side of the November 2002 build split. Confidence: Reported (2/3). Added 2026-10-22, updated 2026-10-22, sources last read 2026-10-22. Sources: Redline Auto Parts (used-parts dealer; hands-on checks, own disclaimer) ; Miata.net Garage ; MX5Global (enthusiast guide site, Oct 2026) #### Will Aftermarket (non-Mazda) NA/NB hardtop fit a Mazda Miata NB (1999-2005 US model years)? URL: https://chassisdex.com/mazda-miata/nb/will-aftermarket-hardtop-fit/ Answer: Yes, with extra parts or work. Aftermarket tops are made to the shared 1990-2005 shape, so they sit on an NB, but the Miata.net FAQ says most (perhaps all) have the old-style front latches and an NA-style defroster plug. On a 1999 to early-2003 NB the latches match; on a car built from November 2002 on, you would need late-style latches. A heated rear window would need the NB-style defroster pigtail. Owner feedback on several aftermarket tops is mixed, so a used factory top is usually recommended. Forum-level and summary sources only. Verdict: Fits with extra parts or work. Years: 1999-2005. Applies to: all NB; cars built from 11/2002 need late-style latches. Confidence: Limited (1/3). Added 2026-10-22, updated 2026-10-22, sources last read 2026-10-22. Sources: Miata.net Garage ; MX5Global (enthusiast guide site, Oct 2026) #### Will 15x8 +28 wheel (4x100), e.g. Enkei RPF1, with 205/50R15 fit a Mazda Miata NB (1999-2005 US model years)? URL: https://chassisdex.com/mazda-miata/nb/will-wheel-15x8-28-fit/ Answer: Yes, reportedly. NB fenders are a little more forgiving than the NA's. A wheel guide lists 15x8 +25 to +30 with 205/50R15 or 225/45R15 on an NB, with a roll recommended when lowered and about -1.5 degrees of camber. An NB owner on the Miata.net forum runs RPF1s with 205/50R15 and reports no rubbing; an owner gallery entry for a 2004 on coilovers at about 4.25 in (front pinch weld) reports rubbing the fender liner under hard cornering until the liner and the fender-to-bumper tab were trimmed. Most 15-inch wheels clear the NB Sport brakes (2001-02 Sport package, all 2003-05), but check your specific wheel design. Aftermarket wheels usually have a larger bore than the 54.1 mm hub, so use hub rings if the wheel is hub-centric by design. Verdict: Reported to fit. Years: 1999-2005. Applies to: 205/50R15; clears factory brakes on common designs; roll or trim liners on coilovers. Confidence: Reported (2/3). Added 2026-10-23, updated 2026-10-23, sources last read 2026-10-23. Sources: rimlist (wheel listings and guides; contains affiliate links) ; MX-5 Miata Forum (includes a reply from Good-Win Racing, a Miata parts vendor) ; Fitment Industries (wheel retailer; owner-submitted gallery) ; Miata Turbo Forum (2023-24; includes a reply from the founder of 949 Racing) ; rimlist (wheel listings and guides; contains affiliate links) #### Will 15x8 +34 to +36 wheel (4x100), e.g. 949 Racing 6UL fit a Mazda Miata NB (1999-2005 US model years)? URL: https://chassisdex.com/mazda-miata/nb/will-wheel-15x8-36-fit/ Answer: Yes, reportedly. On an NB the same wheel is easier still: the SuperMiata table says 225/50 fits NBs fine and 225/45 clears with stock alignment, and a separate wheel guide lists 15x8 +30 to +35 for 205/50 or 225/45 with a possible roll when lowered. The maker says the current 6UL (+34, 67.1 mm bore, lug-centric) clears NB Sport brakes. Short-body coilovers with more bump travel can still bring the tire into the liner. Verdict: Reported to fit. Years: 1999-2005. Applies to: 205/50R15 or 225/45R15; clears NB Sport brakes (maker's claim for the Gen6 6UL). Confidence: Reported (2/3). Added 2026-10-23, updated 2026-10-23, sources last read 2026-10-23. Sources: Miata Turbo Forum (2018) ; 949 Racing (wheel maker) ; rimlist (wheel listings and guides; contains affiliate links) #### Will OEM NA wheel (14x5.5 or 15x6, +45) fit a Mazda Miata NB (1999-2005 US model years)? URL: https://chassisdex.com/mazda-miata/nb/will-oem-na-wheel-fit/ Answer: Yes, reportedly. NA and NB share the 4x100 bolt pattern and 54.1 mm hub, so NA wheels bolt on. The limit is brakes: the NB1 and early base NB2 use the same size front brakes as the 1994-97 NA, so 14-inch NA wheels clear, and a 1999 base NB came on 14-inch wheels from the factory. Owners on Miata.net report running 14-inch NA wheels on 1999 cars with no problems. From 2001 Mazda added larger 'Sport' brakes (on the suspension package, and by some accounts LS/SE) and made them standard in 2003; owners and a wheel guide say 14-inch wheels will not clear those calipers. Sources disagree on exactly which 2001-02 trims had the big brakes, so check the rotor size (255 mm standard vs 270 mm Sport front) before buying. NA 15-inch factory wheels were not confirmed against Sport brakes. NA wheels are +45 versus the NB's +40, so they sit 5 mm further in. Verdict: Reported to fit. Years: 1999-2005. Applies to: cars with standard brakes (1999-2000, most 2001-02 base cars); 14-inch NA wheels do not clear the Sport brakes (2001-02 Sport package and all 2003-05). Confidence: Reported (2/3). Added 2026-10-23, updated 2026-10-23, sources last read 2026-10-23. Sources: MX-5 Miata Forum ; MX-5 Miata Forum ; rimlist (wheel listings and guides; contains affiliate links) ; rimlist (wheel listings and guides; contains affiliate links) ### NB known problems #### NB1 ignition coil packs wear out and can damage the cat (1999-2000 (NB1)) URL: https://chassisdex.com/mazda-miata/nb/problems/nb1-coil-pack-failure/ Severity: Medium. Confidence: Reported. Updated 2026-10-19. Symptoms: Misfires, hesitation, stalling, idle problems. Cause: A forum problem list and a year-by-year page both say the NB1 coil packs fail; the latter says failing coils can damage the catalytic converter. A forum poster notes NB2 uses a different ignition system without this issue. Fix: Replace coils and wires with plugs as a set; same forum thread suggests a cooler NGK heat range for the stock copper plugs. Sources: MX-5 Miata Forum ; miatayear.com #### Thrust-bearing failure in some 1999-2000 cars (1999-2000) URL: https://chassisdex.com/mazda-miata/nb/problems/thrust-bearing-1999-2000/ Severity: Medium. Confidence: Confirmed. Updated 2026-10-19. Symptoms: Rattle with the clutch pedal depressed or when revving. Cause: Road & Track reports thrust-bearing failure in a few cars and a service bulletin; a second source also lists it. Fix: Most have probably been repaired; listen for rattle on a test drive. Sources: Road & Track (Jun 2016) ; miatayear.com #### Clutch chatter in 2001 and some 2002 cars (2001-2002) URL: https://chassisdex.com/mazda-miata/nb/problems/clutch-chatter-2001-2002/ Severity: Low. Confidence: Reported. Updated 2026-10-19. Symptoms: Shudder on engagement. Cause: Road & Track mentions it as an annoyance with the only fix being clutch replacement. Fix: Replace the clutch; R&T suggests a lighter flywheel while you're in there. Sources: Road & Track (Jun 2016) #### Plastic radiator end tanks go brittle; airflow blockage (1999-2005) URL: https://chassisdex.com/mazda-miata/nb/problems/radiator-end-tanks/ Severity: Medium. Confidence: Reported. Updated 2026-10-19. Symptoms: Coolant seepage at the radiator; overheating in hot climates. Cause: R&T says the cooling system is relatively weak, original plastic end tanks can be brittle, and bulky grille accessories or driving lights can reduce airflow. Fix: Budget for an all-aluminum radiator and keep the grille opening clear. Sources: Road & Track (Jun 2016) #### Corroded coolant mixing-manifold elbow (NB1) (1999-2000) URL: https://chassisdex.com/mazda-miata/nb/problems/coolant-mixing-manifold-elbow/ Severity: Medium. Confidence: Limited. Updated 2026-10-19. Symptoms: Coolant leak from the small front elbow. Cause: A forum thread reports the pressed-in elbow corroding and failing; other posters report the same, and similar parts elsewhere in the cooling system. Fix: Replace rather than patch; thread suggests also replacing heater return pipe O-ring and radiator hoses. Sources: MX-5 Miata Forum ; miatayear.com #### Crank and cam position sensor problems (1999-2005) URL: https://chassisdex.com/mazda-miata/nb/problems/crank-cam-sensor-problems/ Severity: Low. Confidence: Reported. Updated 2026-10-19. Symptoms: Stuttering, cutting out, power loss. Cause: A forum problem list and year-by-year page both name the crankshaft position sensor, and mention cam angle sensor seal/gasket weaknesses. Fix: Sensor replacement is called an easy fix. Sources: MX-5 Miata Forum ; miatayear.com #### Rust (front side members, East Coast cars) (1999-2005) URL: https://chassisdex.com/mazda-miata/nb/problems/nb-rust/ Severity: Medium. Confidence: Reported. Updated 2026-10-19. Symptoms: Corrosion in structural areas. Cause: R&T says East Coast cars should be checked for rust; a UK forum poster reported double-skin front side-members rusting badly. Fix: Inspect underbody and front side-members when buying. Sources: Road & Track (Jun 2016) ; MX-5 Miata Forum #### EGR codes and idle drop (1999-2000 (listed)) URL: https://chassisdex.com/mazda-miata/nb/problems/egr-and-idle-drop/ Severity: Low. Confidence: Limited. Updated 2026-10-19. Symptoms: EGR codes 0401/0402, idle dips at a stop. Cause: Listed as common on the year-by-year page only (search excerpt). Fix: The forum mentions an updated plug choice and an off-computer idle adjustment as ideas; unverified. Sources: miatayear.com ; MX-5 Miata Forum #### Oil leaks: valve cover gasket, rear cam plug and front seals (1999-2005 (all NB)) URL: https://chassisdex.com/mazda-miata/nb/problems/oil-leaks-valve-cover-cam-plug/ Severity: Low. Confidence: Reported. Updated 2026-10-22. Symptoms: Oil film on the back or sides of the valve cover, oil running down the back of the head toward the bellhousing, drips under the front of the engine, oil in the spark plug wells, or a burning-oil smell after a drive. Cause: Mazda Motorsports' leak checklist for 1999-2005 cars lists the valve cover gasket, PCV grommet and oil-cap seal, the cam and front crank seals behind the timing covers, the dipstick-tube O-ring, the rear main seal, the oil pan, and on NBs specifically the round cam seal plug at the back of the head (the NB has no NA-style CAS O-ring there). It also warns that oil from the top of the engine running down the back is easily mistaken for a rear main seal leak. Owner reports on the cam plug differ: one mechanic who has done many NB timing-belt jobs says NBs rarely leak there, while another owner says three of his NB engines did and that it is often misdiagnosed as a valve cover leak. Fix: Degrease the engine, run it and trace fresh oil from the highest point down. The cam plug is cheap; owners usually pull the valve cover and rear cam cap to fit a new plug (some reuse the old one with sealant, letting it cure before reassembly) and do the valve cover gasket at the same time if it is hard. Cam and front crank seals are best replaced with the timing belt. Consult the factory service manual for sealant points and torque. Sources: Mazda Motorsports (Mazda's racing parts and support arm, 2020) ; Miata Turbo Forum (2019) ; MX-5 Miata Forum ; Miata.Repair (DIY guide site) #### Soft-top water leaks: blocked drains, side-window seals and latches (1999-2005 (soft-top cars; same drain layout as the NA)) URL: https://chassisdex.com/mazda-miata/nb/problems/soft-top-water-leaks/ Severity: Medium. Confidence: Reported. Updated 2026-10-22. Symptoms: Wet carpet behind the seats or in the footwells after rain or a car wash, water sloshing in the sills, a musty smell, or drips at the front corner of the top by the windshield. Cause: Rain that runs off the top is collected in a rail and drains through two tubes, one on each side, whose openings sit in the corner where the top hinges, between the seatbelt tower and the body, under a flap of carpet. When those drains block, water pools there and can rot the sills. A club tech article covers both NA and NB. Leaks at the front corners are more often down to side-window weatherstrips that have shifted or shrunk, a clogged drain in the front seal, or top latches that no longer pull the top down tight. Fix: Clear both drains: tilt the seats forward, unlatch and tip the top back, fold the carpet flap, and feed a flexible line (trimmer line or a soft cable, not a sharp rod) down each tube, then pour in water to test. For front-corner leaks, owners nudge the side-window weatherstrips toward the windshield so they seal against each other and the glass, and check latch adjustment. A top that still leaks may need new weatherstrips or a new top. See also the NA rust and drains entry. Sources: MX-5 Club of Victoria (club magazine tech article, 2012) ; MX-5 Miata Forum ; Buckeye Miata Club (club newsletter, 2006) ### NB build entries by goal #### First steps: Start with tires, brake pads and driving time URL: https://chassisdex.com/mazda-miata/nb/best-mods/first-steps/#tires-pads-and-track-days-first Road & Track's advice for NBs: buy good tires and pads and spend the suspension budget on track days first; a roly-poly stock Miata helps you learn weight transfer. Caveats: Opinion from one editorial. Confidence: Reported. Updated 2026-10-19. Sources: Road & Track (Jun 2016) #### Suspension: Coilovers, sway bars and strut-tower brace URL: https://chassisdex.com/mazda-miata/nb/best-mods/suspension/#coilovers-sway-bars-and-braces A mod guide ranks coilovers as a top bang-for-buck suspension mod, lists many NA/NB-compatible kits, and says sway bars and a front tower bar tighten handling. Caveats: Listings are from one editorial roundup and were not checked against vendor charts. Safety-critical. Confidence: Limited. Updated 2026-10-19. Sources: Low Offset (updated Sep 2026) #### Wheels & tires: 15x7 +38 wheel and 205/50R15 tire URL: https://chassisdex.com/mazda-miata/nb/best-mods/wheels-tires/#15x7-wheel-and-tire 15x7 is called the standard Spec Miata wheel size; +38 205/50-15 is reported to fit any NA/NB with no modifications. Caveats: Single source for the specific fit; lowered or heavily cambered cars may rub. Confidence: Reported. Updated 2026-10-19. Sources: Race & Track Driving (Mar 2018) ; Low Offset (updated Sep 2026) #### Drivetrain: Limited-slip differential URL: https://chassisdex.com/mazda-miata/nb/best-mods/drivetrain/#limited-slip-differential Hagerty says any NA is one phone call away from having a limited slip; Road & Track says NBs from 2003 use a Tochigi-Fugi LSD instead of the Torsen and that both beat an open differential. Caveats: Check what your car already has: NA 1990-93 viscous option; Torsen optional from 1994. Confidence: Reported. Updated 2026-10-19. Sources: Hagerty Media (Mar 2021) ; Road & Track (Jun 2016) #### Drivetrain: 6-speed and LSD swaps within the NB family URL: https://chassisdex.com/mazda-miata/nb/best-mods/drivetrain/#nb-6-speed-and-lsd NB drivetrains interchange widely: the 6-speed bolts into 5-speed cars with its own shifter, and 1994-2005 1.8 rear ends swap freely except the Mazdaspeed unit, which needs its own axles. Caveats: Match final-drive ratio to the gearbox. Confidence: Confirmed. Updated 2026-10-20. Sources: Redline Auto Parts (used-parts dealer; hands-on checks, own disclaimer; Dec 2018) ; MX-5 Miata Forum ; Redline Auto Parts (used-parts dealer) #### Cooling: All-aluminum radiator URL: https://chassisdex.com/mazda-miata/nb/best-mods/cooling/#aluminum-radiator R&T says to budget for an all-aluminum radiator if the original plastic end tanks are leaking. Caveats: Part choice not sourced here. Confidence: Reported. Updated 2026-10-19. Sources: Road & Track (Jun 2016) #### Power: Forced induction and engine swaps URL: https://chassisdex.com/mazda-miata/nb/best-mods/power/#forced-induction-and-swaps R&T and a mod guide say turbo and supercharger kits are common; the Mazdaspeed's non-VVT head and lower redline limit big power; buying someone else's finished build is cheaper; and the clutch needs upgrading at higher power. Caveats: No kit is recommended here; no power figures are verified. Confidence: Reported. Updated 2026-10-19. Sources: Road & Track (Jun 2016) ; Low Offset (updated Sep 2026) #### Brakes: NB2 Sport brakes on a 1999-2000 NB URL: https://chassisdex.com/mazda-miata/nb/best-mods/brakes/#nb2-sport-brakes-on-nb1 A factory-parts brake upgrade for NB1 cars: Sport calipers, brackets, rotors, pads and front lines from a 2001-05 car, with trimmed dust shields and wheels that clear. Caveats: Safety-critical; dealer and forum sources only. Pedal feel changes unless the master cylinder is addressed. Confidence: Reported. Updated 2026-10-20. Sources: Redline Auto Parts (used-parts dealer; hands-on checks, own disclaimer; Dec 2018) ; MX-5 Miata Forum