Tip placement makes a difference, believe it or not...try having it extend past the muffler and don't use a rice tip.
when I got my vr4, the guy put a big ole rice tip on it and it was far behind the bumper (under car) and damn what a difference putting a 3" tip (the exh size) and proper placement. I have a small SS ovak stright thru glasspack-type, fwiw...