kwawd, kim aka kj380 is selling magnaflow and berklee mufflers. best to get one of them and then the hm headers. as wytwun mentioned, the straight through muffler will bring your flywheel power from 154kw to 159kw. adding the hm headers will increase it to at least fwd sports/vrx flywheel power of 163kw plus a couple more to 165kw.