Mazdaspeed downpipe/catalytic converter upgrade
Mazdaspeed downpipe/catalytic converter upgrade
Exclusive to Flyin' Miata!
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Description
Replace the restrictive and heavy downpipe on your Mazdaspeed with this 2.5" stainless steel version. When combined with our Mazdaspeed exhaust, it offers noticeably faster spoolup and a good increase in power. We measured a 23 hp and 26 lb-ft increase on our dyno. If Mazda had delivered the car like this from the factory there would be a lot less interest in aftermarket upgrades! An extremely popular upgrade for Mazdaspeeds.
Beautifully made out of stainless steel with polished flanges, this is a long-lived upgrade. So long that we offer it with a lifetime warranty. Details. It`s also 7.2 lbs lighter than stock as an extra bonus.
As with all of our catalytic converters, this cat is emissions-certified. Specifically, it's EPA-approved for this application. Please note that these are not CARB legal and we cannot ship them to California. They're also not legal in states requiring CARB cats. That's California, Colorado, New York, and Maine.
5 year/50,000 mile warranty on the catalytic converter body, the internals (and ability to pass an emissions test) are covered for 25,000 miles, everything else is covered for life. Fits the Mazdaspeed with stock turbo only.
Instructions
Shipping
Details
Shipping restrictions: Cannot be shipped to California, Colorado, Maine or New York
What does it fit?
Fits: 2004-2005 MSM
Emissions
50 state legal!
CARB EO: None
Warranty
lifetime
SKU
The initial spool of my turbo has been lowered by at least 500 rpm. Im new to my mazdaspeed miata and logged about 300 miles on it before upgrading the exhaust. I paired it with the flying miata mazdaspeed exhaust and midpipe. I also added the matsudah triangle gasket. If your gonna try this yourself, you'll need a 14mm swivel socket, a long extension whether 3/8 or 3/4 drive, most likely 3/4 to get some long handled torque, but clearance is tight and your mileage may very depending upon your wrist strength. To help i recommend a good penetrant oil, something like rust buster... save the wd-40 for the exhaust hangers. My car had 36k miles in 2026 and I still fought a battle and became saturated in oils and gross a** rust.
My '04 MSM started to rattle. Mechanic diagnosed as bad catalytic converter in my FM downpipe, quoted $$$ to replace. I bought another downpipe and saved hundreds, though i got teased for bringing him such big box for a cat.
Great upgrade as everyone says and it also fixed the P0420 problem. Turns out the cat failed and replacing it was the best solution. Had this installed back in June and after 5 months and 2500 miles, CEL has not come back since.
After putting this on it made a major difference on the car and no CEL. Would definitely recommend for any Mazdaspeed ower as the turbo spools significantly quicker.
2 notes:
it does not come with the triangle gasket for the turbo to mount to the downpipe, it does come with the 2 bolt exhaust gasket though
Welds were solid but there was some splatter and not the prettiest (who cars though it's under the car where noone will see
Thanks for your review, Adam! We're glad to hear you're pleased with the upgrade! The three-bolt gasket at the turbine outlet can usually be reused since it's a stamped steel gasket with a dimpled inner lip. However, we do sell those factory gaskets separately if you aren't sure what shape your gasket is currently in: https://flyinmiata.com/products/gasket-msm-outlet-downpipe-2004-05
I had a local shop install this downpipe. They were pleased with the quality. Likewise, I was pleased with the result. The increased flow allows the car to connect assuredly at the right power level, instead of the factory ‘hole’ from 3000-3500 rpm. This is a completely ‘bolt-in” change that bring the entire powertrain in line with its purpose but also becomes a more drivable car at more rpms. Noise increase is there but subtle...I noticed but my son didn't. Icing on a cake!
