my personal favorite has always been Borla. ran em on 75% of the vehicles ive had, the other 25% was always straight pipes. cant go wrong with the XR Borla mufflers man. back pressure is one of those things that the queer racers like to blame on wen they lose. its true u lose some hp/tq downlow but wen ur wide open ur not losing anything, ur gaining. couple gaggots already said, no restrcition=more power, cant get no truer than that other than sayin theres no replacement for displacement.