higher flow mufflers.. haha.. we won't get into that. but i would check that.. when i installed my headers my downpipe was hitting the floor when i would gun it. ended up just flipin stock motor mounts and that was enough to keep it from hitting.. but that's on 2003.. don't know how much differnet the newer ones are. but if flippin mounts is as easy for yours i'd try that.. unless your positive it's not the exhaust