Since Im going with a custom 2.5 or 3 inch single exhaust, and my N/A S2K hardly has any mods, should I use my stock cat or unresonated test pipe for more power?

 

testpipe will always yield more power then going with a cat...

 

yield meaning gain right?

 

That's right, Ztop

 

Power gain,with a T.P.on a hardly stock engine,will be minimal.
Fine could be quite substential,up to $2500.00.

 

stay w/ the stock cat, not worth polluting the environment and potentially getting a HUGE fine.

 

stock.

 

does it get loud with a testpipe on stock exhaust?

 

No it does not get loud. Volume may be slightly increased, but the sound definately changes. It sounds more raspy/ricey. I prefer the sound with a testpipe, but gains were very minimal if at all, the exhaust smells, and it gets your exhaust tips/bumper dirty. Maybe I'm the only one, but I regret spending $100 for a testpipe. Any environmental nuts wanna pay me $100 to put the cat back on my for me? Haha.

 

go with the testpipe