I’ll be honest, I’m kinda confused on what you’re wanting to do with the n54 downpipes. Just put a cat in the midpipe and call it a day. There’s more space and less headache.
So I’m trying to keep the car looking as stock as possible due to the smog tests in California. I’m not worried about it passing but would like to keep things close to stock. N20 down pipe looks like it could fit with the least modification. I know this is very hard in the space given but it’s worth a try so just looking for information.I’ll be honest, I’m kinda confused on what you’re wanting to do with the n54 downpipes. Just put a cat in the midpipe and call it a day. There’s more space and less headache.
cool thank you for the information I’m thinking about if I should now I’m only planning to boost up to 425 at most to start that’s why I was asking about the cats staying as you were saying it won’t be much boost power. Any shops they would recommend for the inspection?You’re not gonna fool anyone into thinking your car is stock if there’s a turbo on your m3. Additionally an stock n20 down pipe, or any other oem down pipe for that matter, will not be able to flow enough to make any marginal power. The stock downpipes will make a whole load of backpressure and make your egts go sky high. You might be able to get 60-70ish more hp out of your m3 with a turbo on an oem downpipe, but not much more. You can get close to the same gains with NA bolt ons. If you are determined to boost your m3 and keep it emissions agreeable and actually make notable power gains over stock, you should supercharge it instead. All of the cali turbo bmw guys I have talked to “know a guy” who will pass snog for them, and if you don’t know a guy, you’re not gonna pass.