I hear many phrases describing exhausts such as cat-back, freeflow, tri-flow, etc... What exactly do these terms mean. Also, how good is the stock M3 exhaust (compared to aftermarket - performance-wise) and what "type" is it. Has the M3 exhaust changed thru models years '95 - '99? Would a '97 M3 exhaust for $200 be a good upgrade for a 325i thats got hi-flo air, bilstein/H&R sport suspension, Jim C. chip, M3 wheels and body kit (this is what my 325i has so far).
Thanks in advance.