As I'm sure you've noticed, the guys on this board are huge on hawk. Good product, and very affordable.
I would suggest you stay away from Jardine. Nobody seems to have really positive experiences with their products on Buells.
I, and a few other boys on the board, use the GB exhaust. While it isn't the cheapest option, and it does require that you ride without a chin fairing (which I actually prefer, anyway), I think I can speak for all of us in saying that it's an excellent product. George is a stellar guy, the exhaust performs excellently, and it looks great. That's just my two cents, though.