Quote:
Originally Posted by B_2_B_P
I just don't know how big(tube size) I can go without getting into trouble. I don't know where to look either.
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If the car already uses 2.25" and you buy an exhaust system that uses 2.25, the only things you will gain are better bends and slightly better flow/sound from the muffler. Remember, the factory system is a compromise of performance, cost, and longevity.
Going up to a 2.5" (after the cat) is only a marginal increase, but the slightly larger diameter will allow a marked increase is exhaust flow. The engine is an air pump and improving the engine's ability to inhale and exhale will help it perform better. Granted, everything pre-cat hasn't changed, but altering that will not go over will with CA emissions peeps.
If you were going forced induction, a 3" system would yield better results, but if you are staying NA, I wouldn't go above 2.5"
UUC uses Corsa mufflers, but only makes a 135i system.
Turner Motor Sports has a 128i project car. However their exhaust offerings (Borla, Corsa, and SuperSprint) are labeled for the 135i.
Hottexhaust.com sells magnaflow products, but again, only lists the 135i.
There are loads more vendors, but I'll let you do the looking.