i dont think actual testing has ever been done......but the consensus seems to be the most power robbing part of our exhaust, besides the crappy headers and the poor flowing exhuast manifold......would be the resonator.....that would be the place to start......get something free-flowing like dynomax and magnaflow....i have magnaflow and love it.......buy you some magnaflow components and have a shop build you the rest from the cat back........hope that helps......

-chris-
96 gl: 18" adr reactions, SVT rear bumper & side-skirts, Magnaflow exhaust, CTA Intake, ACCEL coil, 9mm wires, Kenwood, Blaupunkt, Sony Xplod Mobile ES, OBX pedals w/dead pedal, neons, bnmotorsports gauges, autometer monster tach, and ZAINO!