Before my V-8 install, first I removed the rear cats, louder but not much, then I removed the resonator, louder, then I put the resonator back on and remove the muffler, all with the rear cats still remove. Then of course we install the V-8, the resonator and the muffler went back on the car but there are, when I stop for a red light at quiet, when the light turned green and I leave, everyone turns her head and looks to see what the hell was that. Good luck Jim