Ok question while we're on the subject...why do all the import guys do a header BEFORE the exhaust? Or at least I seem to see that order recommended alot...with domestics it was completely opposite, doing headers and trying to push the added flow through the restrictive factory exhaust was really pointless.

As an example a buddy of mine put a set of long tubes on his Z28 and he gained 6hp at the peak and about 9 hp at redline...he put on an exhaust after the headers and gained 23hp peak and 34hp at redline. Under normal circumstance you would NOT see that kind of a gain from an exhaust on a Z28...the big portion of that was due to the headers...

So why the opposite on the import cars?