Dar covered everything quite well as usual...Except, the reason you get the black residue out of the muffler, even though the bolt is tight, is because there's a baffle disc inside that "frets" and there isn't much you can do about that. Except maybe remove it, but then you wouldn't have enough tank pressure. If you can figure out a way to keep that alum. disc from chafing/ fretting let me know! I tried JB weld, silicone, but they disintegrated...