Parts/Miata
Miata · Buyer's guide

US NA/NB Mazda MX-5 Miata Factory Rear Muffler-with-Pipe and Main-Silencer Identification

US 1990-1997 NA and 1999-2005 NB Mazda MX-5 Miata factory naturally aspirated rear muffler-with-pipe/main-silencer branches only. Match generation, production, engine/turbo status, transmission, emissions equipment, upstream flange, hangers and bumper-tip interface. Exclude the US 1998 gap, 2004-2005 Mazdaspeed turbo, NC/ND, non-US/RHD assumptions, manifolds, front pipes, catalysts, oxygen sensors, universal/race systems and cut-and-weld conversions.

Current seller options

WHERE TO BUY

Open an exact listing, then confirm fitment, stock, price, and shipping with the seller before ordering.

Seller links checked . Prices and availability can change.

What you need to know

Start with recipient and donor VINs/build dates, NA versus NB, naturally aspirated versus Mazdaspeed, manual versus automatic and the installed main-silencer number. Photograph and compare the upstream flange or donut seat, pipe diameter and clocking, hanger count/locations, case and tailpipe geometry, bumper-tip clearance and any welded repair. The NA rear system and NB rear-muffler interface are not the same layout; some checked NB aftermarket mufflers exclude 1999-2003 automatic cars or require a matching midpipe. Itemize the muffler/case, attached inlet and tailpipe, tip, gasket or donut, flange hardware, hangers/isolators and heat shielding. Reject perforation, severe scaling, crushed or kinked pipe, cracked seams or brackets, loose internals, warped flange, broken studs, impact/freight damage, undisclosed cuts/welds, altered tips, missing hangers or unknown catalyst-boundary modifications. Retain the factory catalyst and lawful emissions configuration; verify local sound rules and use stable lifting plus qualified exhaust service.

OEM numbers

CHECKED FACTORY MAIN-SILENCER IDENTITIES, NOT ONE NA/NB INTERCHANGE. NA manual: BP55-40-100D for checked 1990-1995 and BPA5-40-100B for 1996-1997. NA automatic: B6B4-40-100F for 1990-1993, BP59-40-100D for 1994-1995 and BPA6-40-100B for 1996-1997. NB naturally aspirated 1999-2000: manual BPM3-40-100G and automatic BPM1-40-100Ea checked seller path reports BPM1-40-100D as the predecessor to E. Later naturally aspirated NB: current manual service identity BPP6-40-100C with checked earlier BPP6-40-100, A and B family entriesautomatic BPM8-40-100G with BPM8-40-100H beginning at the checked 2004-10-01 production split. Exact 2005 and every used donor still require VIN/build, installed number and turbo/transmission confirmation.

Supersession

The checked current seller catalog reports BPM1-40-100E replacing BPM1-40-100D and BPP6-40-100C replacing BPP6-40-100, BPP6-40-100A and BPP6-40-100B. Those are seller-published service chains, not proof that a complete rear assembly crosses NA/NB, manual/automatic, early/late production or turbo boundaries. BPM8-40-100G and H remain a production split, not a suffix-free universal chain. No Mazdaspeed BPS7-to-standard-NB or NA-to-NB supersession is asserted.

Fitment

Start with recipient and donor VINs/build dates, NA versus NB, naturally aspirated versus Mazdaspeed, manual versus automatic and the installed main-silencer number. Photograph and compare the upstream flange or donut seat, pipe diameter and clocking, hanger count/locations, case and tailpipe geometry, bumper-tip clearance and any welded repair. The NA rear system and NB rear-muffler interface are not the same layout; some checked NB aftermarket mufflers exclude 1999-2003 automatic cars or require a matching midpipe. Itemize the muffler/case, attached inlet and tailpipe, tip, gasket or donut, flange hardware, hangers/isolators and heat shielding. Reject perforation, severe scaling, crushed or kinked pipe, cracked seams or brackets, loose internals, warped flange, broken studs, impact/freight damage, undisclosed cuts/welds, altered tips, missing hangers or unknown catalyst-boundary modifications. Retain the factory catalyst and lawful emissions configuration; verify local sound rules and use stable lifting plus qualified exhaust service.

Aftermarket options

A direct-fit replacement rear muffler may be compared only when the maker states the exact NA/NB year, manual/automatic exclusions, naturally aspirated or Mazdaspeed branch, upstream flange or required matching midpipe, hanger and bumper-tip geometry, sound/legal status, included gasket/hardware and warranty. Checked seller examples demonstrate separate 1999-2003 automatic and Mazdaspeed paths. Universal, race-only, catalyst-delete and cut-to-fit systems are outside this factory rear-muffler identification claim.

Before you buy

This is not universal NA/NB, manual/automatic or standard/Mazdaspeed exhaust interchange. Match both VINs/builds, installed number, upstream flange, pipe clocking, hangers, bumper clearance and written contents. Preserve the factory catalyst and emissions configuration. Reject perforated, crushed, cracked, internally loose, cut/welded, incomplete or freight-damaged assemblies; seller stock and fitment remain dated observations.

Research and fitment sources