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MX5 Miata Street Header features:
-Longer, equal length runners
-High-flow 5" round, 200cpi Ceramic Core Catalytic Converter
-49 state legal cat (EPA and OBD2 compliant, but NOT CARB APPROVED for California, the Carsound 99659HM core is an EPA certified converter covering up-to 6.2L/6375 lbs so it easily handles the flow of our performance header while still delivering clean tailpipe emissions)
-Bolt-in design for MANUAL TRANSMISSION (see our forum header install thread for details of installation on automatic transmission).
-Bolts to RoadsterSport MX5 Midpipe...or stock MX5 midpipe. Also saves weight, factory header assembly is 15.2 pounds and this RoadsterSport MX5 Street Header with converter is just 11 pounds! Converter has two year manufacturing defect warranty (normally aspirated cars only, NOT recommended for supercharged cars), the rest is all stainless steel and has a LIFETIME warranty, even the flanges!
Currently for Manual Transmission only (a professional can install on the automatic but it requires re-engineering the cooling line layout and modification to the bell housing). Also, sorry to our Australian customers but this fits Left Hand Drive only.
We have included a number of extra features into our MX5 Miata Street Header which we believe customers will appreciate. We CNC machine the main flange to match the factory unit, including the bolt hole flange area thicknesses so that we are precisely replicating the factory fit to the head in terms of thread depth and space, etc.
Our collector outlet is 2.5 inches. Curiously, the factory outlet is ALSO 2.5 inches and then the factory exhaust chokes down after that point. For best HIGH RPM performance customers should match our header with our midpipe and exhaust so they are running 2.5 inches of flow all the way...but our header will bolt in place of the factory header and connect perfectly to the factory midpipe for better performance from idle to redline.
PICTURE OF FACTORY MX5 HEADER BELOW, Note the pinch point where the factory header suffers the primaries pinched in half, circled in red below. That pinch point chokes the power this Miata 2.0 motor can otherwise make. Our Roadstersport Street MX5 Header eliminates that pinch point, extends the primary length to max torque gains, while retaining a high efficiency converter.
BRIAN'S APPLICATION NOTES: We pushed the converter as far down against the lower flange as possible to maximize the length of our primaries to maximize the torque gains. Dyno Below shows results of configuration we expect most will run (RoadsterSport Street Header with Roadstersport Q midpipe and Roadstersport Q muffler). Low line best results with stock intake and stock exhaust, high line is results with this Roadstersport Street Header, Roadstersport Midpipe and Roadstersport Q exhaust (still stock intake). We expect many will leave factory midpipe in place and use this header with our RoadsterSport Q Muffler on the end (factory midpipe just a little smaller in diameter and we expect that keeping the factory midpipe would give similar results through the low and mid range and give up just a bit toward the high RPM range).
Notice O2 Bung BEFORE and AFTER Converter so you can keep your factory O2 Sensors inline and prevent engine codes. You can use the extension cords linked below, or you can release some O2 wire length from factory harness bracket to make the install without the extension cords (just follow the O2 cords back until you reach that bracket and this will become obvious).
Notice in dyno that the gains in torque are strongest at the low rpm range but extend through the mid range and all the way to redline, that's a torque improvement you can feel every time you pull away from a stop and every time you grab a higher gear! These are dyno results without doing a tune, adding our MotoEast Tune would add even more to your results.
HEAR the RoadsterSport Street Header for yourself on our 2012 PRHT Project Car along with our RoadsterSport Midpipe and RoadsterSport Q Muffler.