i have a 99 civic si & i'm gonna put in a nissan t3. i was wondering if removing the catalytic would be better & what size exhaust tubing. will it be suoer loud? i know someone with a 1g eclipse awd turbo & he doesn't have a cat & he's using a 2 1/2" exhaust tubbing & it's not loud at all. my car with headers & a ca int. is louder than his.

 

yea, i actually noticed mine being a little quieter after putting on turbo. i used 21/4 and gutted cat. i think it helps to remove cat.

 

what size exhaust tubing is best? 2 1/2" id or 3" id.

 

i would go w/ 3"...but you could get away with 2.5" w/ no cat.

 

ima remove the cat cause we dont have emission laws in florida no more but i dont know if i need back pressure or what & if i should go with the 3" ima do some more research on that i wont install a new exhaust til maybe 1 month after i install my hmt

 

If you need to obey emission then get a high flow cat if not remove the cat if you want and put on an extra resonator unless you want it to be loud.

 

if yer running an internal wastegate, it might be more benifitial to run 2.25" or 2.5 inch. sure you will get most hp if you go 3", but the wastegate might not work correctly if you lose all backpressure in the pipe.

 

Youll just boost a bit higher.

 

then 3" it is! thanks guys. i realy don't think it'll be too loud, i know a guy with a eclipse gsx & he hsa a 2 1/2" exh. & no cat & my car sounds louder than his & all i have is headers & a str8 through muffler but mines not turbo. he says tubo cars r quiter.