i think i lucked out. i have enough air coming in, that relieveing a lil backpressure was benificial. basics of a motor are more air in requires more air out. on a straight stocker, yeah, it'd prolyl do more bad than good. but, i'm gonna experiment w/ slightly larger diameter piping for my exhaust. really, i juss wanna eliminate the nasty ass crush bent area from the factory. mandrel bends will hopefully help a lil more.