You get all kinds of opinions but it seems like the hp results are minimal. I have read that the Scorpion slip on porivdes the best gains, bringing the bike to 112rwhp. I also read that the Triumph/Arrow full system provides the best performance gains because it reduces so much weight from the bike. I am running stock and will probably keep it there as I am not into the extra sound for the sake of sound. For further confusion, search around
http://www.triumph675.net/forum/forumdisplay.php?f=13
