Originally Posted by bubbleman
instead of buying a testpipe go to your local parts house and get a piece of pipe and 2 clamps, shouldn't be more then 15 bux
you'll lose very little low end but at about 4300 rpm you'll be able to watch your rpms climb quicker, and you'll feel a difference
put your car on a diet also
WTF...you say "Instead of a testpipe..." then you go on about telling him to get a testpipe made???
Anyway, the cat is a restriction on the exhaust system and should be considered as piece to be upgraded. Only good it does is on a stock exhaust system. If you want to run a higher flow all the way through, get a carsound or other high flow cat's. Like I said, same performance without the crappy noise and air pollution.
Whether you upgrade the cat or the header first makes no difference as long as you plan on upgrading both. Your only hurting performance by getting a higher flowing header and exhaust piping while keeping the stock cat.