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We outfitted our Project 2012 PRHT Miata with a computer and sound spectrum analyzer and microphones and drove it under varying conditions and loads with mufflers and without any muffler to measure the frequencies coming out the midpipe. We then use that data and some special software to calculate the particulars of the Helmholtz chamber needed to precisely knock down the frequencies we do not want to hear while allowing the good throaty burble fun sounds to pass through. The result is all the fun, an almost exotic burble throaty result, without the drone! Note it is very dual personality because the effect of the Helmholtz is very frequency specific such that under decel it is mild and quiet, yet when you push hard toward redline it sounds exotic and racy. With the top down lots of fun throaty burble, but dramatically more tame when the top is up. In brief, FUN when you want it, and mild when just cruising.
Designed as a bolt-on replacement for the factory midpipe to carry higher flow all the way out any of our mufflers. Works with ANY of our muffler choices and customers report great results with everything from our RoadsterSport line to the original MazdaSpeed Mufflers. Simple Bolt on.
INCLUDES TWO O2 SENSOR bungs which gives YOU the option to later add our RoadsterSport headers and avoid engine codes (by using our O2 plug and play extension cords to relocate the factory O2 sensors to before and after the converter in this midpipe).
All stainless steel construction for years of driving pleasure. This MX5 Miata midpipe is larger diameter than stock for superior flow, particularly when matched to our headers. Uses high quality SPUN catalytic converter with metal core (despite presence of converter this unit is not CARB approved...which makes it legal in California only for off-road/race track use).
This midpipe will raise the final sound level because of the higher flow larger diameter tubing and because the Helmholtz is frequency specific in operation.
SORRY, NOT CARB APPROVED, NOT LEGAL ON CALIFORNIA HIGHWAYS. Sorry, we will not ship these to residents of California.
Read full installation hints and notes in our forum Installation Instruction Section! (Click "Forum" at the top of our site, go to installation instruction section, and look for NC/ND Midpipe install thread).
STR LEGAL under Class Rules Update 2012. Pursuant to SCCA 14.10.E: our cat fits entirely in the space that the factory cat occupied pursuant to SCCA 14.10.E....and Magnaflow certifies the core for use in any application <6.2L and 6000 pounds. Core has 25,000 mile manufacturing defect warranty (no core warranty for boosted or track cars), and the rest (including housings) are stainless and include a lifetime warranty.
BRIAN'S APPLICATION NOTES: This is the ultimate Miata Midpipe and it's a serious revolution in Miata exhaust tech, the secret sauce to making a great sounding Miata exhaust system. I never seriously considered less than our RoadsterSport SuperQ as appropriate for the NC Generation Miata using any performance header upgrade but this midpipe makes ALL our choices MUCH more fun. The nature of this style of resonator is that the targeted frequencies are much LOWER volume and other frequencies not targeted are LOUDER than with our standard midpipe. This dual nature of the performance means when you are hard on the throttle it is LOUDER than with our standard midpipe, but on decel or running in the low rpm ranges where these cars tend to drone this setup is much quieter than our standard midpipe. You get all the racy fun, without the drone.
A little on the science, we targeted 120-130 hertz range which is where most folks report uncomfortable 'drone' or 'boominess' and got a total of 48 decibel max drop right at the 125 hertz level...which is a MASSIVE reduction. Nonetheless, looking at broader range we get an average 20 decibel drop from 115 to 138 hertz with reasonable 8 decibel drop in the ranges of 95 to 115 and 138 to 180 hertz. When used with our RoadsterSport Street header and SuperQ the result to my ears was so calm and collected that I think many would not realize the car was modified. When used with our RoadsterSport Max Power header and SuperQ the sound is certainly still louder than stock and almost exotic when on throttle, fun running through the gears and yet when you back off the throttle and just cruise down the freeway very controlled (no issues listening to music or your passenger, etc).
Shot on our Project 2012 with our RoadsterSport Street Header, RoadsterSport Helmholtz Midpipe, RoadsterSport SuperQ Exhaust. In this first sample notice what you do NOT hear, I get on it briefly and then engine brake almost down to a stop and during that engine braking the system gets more and more quiet where normal systems would drone as you engine brake down through 3000 rpms to 2000 rpms.
Second Video Sample: Shot from the bumper this clip massively exaggerates the volume but notice again what you don't hear, lots or racy sound when on throttle but every time I close throttle it quickly gets quiet instead of drone like many systems.
And now a more complete driving sample with camera in the driver's space: INTERNATIONAL SHIPPING NOTES: We only ship to USA and Canada but we do have dealers outside the USA. CUSTOMERS IN EUROPE CAN GET THESE IN EUROPE AT THIS LINK!CUSTOMERS IN Australia CAN NOW GET THESE AT THIS LINK!
Installation Notes: May not clear some aftermarket braces such as Beatrush. Clears our own braces and factory braces. This is MUCH bigger than factory midpipe and install needs careful attention to detail, some fiddle time with the slip joint to get it adjusted just right is normal to get it hanging just right when you are stuffing something three times bigger in the available space. Adjust it too long at slip joint and it will hang too low and bang braces, make it too short at the slip joint in the middle and it will sit too high and tap the differential housing. For these reasons, a professional muffler shop install may be required. You can spend 20 minutes on the first try and not have it right, or spend more time and get it right, we suggest more time up front to make sure you have no points of contact (grab finished install and yank in all directions to see if hit taps anything, adjust again if it does). Note the Helmholtz valve is temperature sensitive, if you live in cold climate just understand it will not do much for you on cold morning starts UNTIL the system is up to normal operating temperature.