ISR Performance Circuit Spec Exhaust for Mazda Miata '94-'97 1.8L

Update: I removed the optional test pipe and installed a bolt on magnaflow direct fit cat, it only took 30 min, it’s not as loud, check engine light is gone (bank 2 o2 will come on with 94-97 if you run it without a cat) and a lot of the drone/raspy/tingy Ricey tone went away. It sounds a lot cleaner with a cat and I can drive it without getting a headache. It IS still loud when I get on it. Considering installing a vibrant resonator. ISR’s customer service is awesome by the way.TL;DR versionPros: Looks good, fits great, completely bolt on, sounds good, feels good, bypasses cat, comes with 2nd o2 sensor bung (which hasn’t thrown a code yet for running no cat), matches all hangers perfectly, clears my rear lower subframe brace With no issues. I love the big side mount tip, awesome design. No ill-fitting pieces...nothing, everything fit perfectly, PERFECTLY, on the first try. That means a lot. Like I said later, attention to detail always wins for me.Cons: It’s a little raspy and ricy in the higher RPMs for my taste. Like, really loud. Bypasses the cat...I thought this was a catback...looks like it eliminates it all together. Other than that I love it, just wish it wasn’t so loud.Ok first off, it arrived quickly, fits great, and sits TIGHT (because I bought no exhaust hangers too, great idea, no rattle, tingle, NOTHING). It has all the gaskets you need, even bolts, and the MAIN reason I got this over the similarly priced Yanaka exhaust, Attention to detail! These guys have a 2nd o2 bung already mounted for us with the 96-97 and a simple screw in block off plate if you don’t need it! That’s perfect for this application. I was hoping for a deeper and throatier tone all throughout but she starts to scream about 3-4K rpms. Lastly, I thought this was a catback exhaust. Last night I’m freaking out trying to find a new catalytic converters because the studs on mine snapped. Then I laid everything side by side and realized this was the same length...with the cat still on the old one. So I bolted it all up and bypass the cat completed. Works great. Power gains? Get real, it’s a bolt on “catback”...but actually it’s a lot more responsive. Probably 5% actual better airflow from the larger exhaust and 95% from ditching my clogged up cat, resonator and old collapsing muffler. But hey, works for me! Side note BUY EXHAUST HANGERS WITH THIS, YOU WILL THANK ME. Nothing worse than a brand new exhaust clinking and clanking like the old one you just got rid of, because you forgot to buy new exhaust hangers. Your old ones are tired and sagging, just spend the extra $6 for some fresh ones. Good luck!

The box it was shipped in had a hole in it and whoever packed my items didn't give a shit. The mounting hardware wasn't bagged up and was falling out of the box as thearly guy handed it to me off his delivery truck, it also came with 1 extra gasket (not really an issue). The exhaust is much louder in person than expected, the sound is amazing, really it is. There isn't another miata exhaust like it, however I STRONGLY recommend you only buy this if you own a hard top, or have sound proofed your trunk and rear tunnel area. I saw this because the exhaust drone is very awful at 55mph to 65mph with the 5 speed transmission. The large muffler included makes your trunk act like an ear for vibration and noise. This exhuast may also not be allowed on some tracks. It makes lots of pops on deceleration which makes me feel like a gitty school girl. I got mine with the resonater and not the test pipe, if it didn't get rid of the pops I would have also looked into keeping the stock cat or maybe purchasing a high flow cat to help with some of the droning. The welds areally great, and if they botch your mounting hardware, just take one nut and one bolt to a local parts place and ask for the thread in a grade 10, get a locking nut with the teath and do not get a washer and lock washer, they will back out.

After dealing with the previous owner cutting off the flange this bolts up to it went very smoothly. This kit includes a resonated cat delete. I bolted mine up to the stock header and front pipe and it sounds amazing. Very deep under 3500. Little bit of rasp between 3500-600 but it sounds good. This is one of those exhaust you buy and it's one and done. Comes with new bolts extra gaskets fits spot on very close to the ppf but doesn't rub it. Will do an update if there are any issues but over the last 12 hrs it's everything you'd expect to get out of a 350 exhaust. Great quality welds too

I installed this on my ‘94 Mazda Miata and I can’t believe how good my car sounds. It’s very loud but a perfect pitch- not ear ringing loud. I get so many compliment on the sound of my Miata. Highly suggest this exhaust

fit perfect with no modifications required and sounds fantastic!