Our take on the classic 4 to 1 Miata header! The most bang for your buck, with all the features you need in an all stainless steel header.
Manufactured entirely from 304-stainless steel with thick flanges that will not warp like other stamped or cast flanges. Large 1.7" primaries collecting to a 2.375" OD tube via a smooth 4:1 merge.
Now UPDATED to include TWO O2 sensor bungs: one right after the merge, for your primary O2 sensor, and a second bung further down by the outlet flange which you can use to add an auxiliary wideband sensor, or use it when you go to the dyno for the sensor that's hooked up to the dyno, etc. All without having to weld in an extra bung later.
Manual transmission only. EGR compatible.
Gasket included for the connection to the cat pipe. You re-use your factory gasket for the engine to header connection as that is a metal sheet gasket and not a crush gasket, it is good for the lifetime of the car.
Comes with a plug loosely installed in the oxygen sensor bung. MAKE SURE to tighten these down where you are not installing an O2 sensor.
Now updated with a SECOND o2 bung down near the outlet flange, which you can use it to add an auxiliary wideband sensor, or use it when you go to the dyno for the o2 sensor that's hooked up to the dyno, etc. All without having to weld in an extra bung later.
Note that adding any header results in an increase in the exhaust sound level on your Miata.
Note there is an INTENTIONAL small dent in one of the primary tubes for clearance to the steering rod.