Originally Posted by
nagger
your right, someone correct me if im wrong but, when boosted (turbo wise at least) you want the exhaust gas to exit the car/exhaust rather quickly, due to the turbo being there, and having less resistance against the fins/turbine in general. thus quicker spool etc etc. better boost overall.
a 3 inch exhaust on a stock motor really wouldnt do anything greatly better than a 2.5 really, unless you want the sound of your car to be alot louder. (not something i suggest in VA). but the BIGGER BORE, higher compression motors these use 3 inch collectors, to 3 inch exhaust if one is present, due to the fact of the higher compression and the more flow. but usually have a fine tuned header (smsp, RMF, etc) because the design of the header usually keeps the right amount of backpressure wanted for the n/a build.
hope im right in thinking that.
You are right about the turbo, less back pressure= less resistance&faster spool with turbo. Now if I was running anything bigger than a ko4 I would run straight 3". I just dont understand the n/a cars running 3", it seems to be more detrimental than helpful. If i am wrong correct me, just trying to get some clarification.