no one has mentioned ebc 320mm super moto rotor and adpater bracket.
tpi has em listed in their brakes section http://www.tpimotorcycleparts.com/
i used these rotors to upgrade my klr brakes and the stopping power is unreal but in the dirt you actually have better modulation that the stock one because the stopping power is very linear. i'd match this rotor w/ a ebc red/carbon pad so you don't overbrake in a panic.
if you really want to stop now (or your a BIG guy who needs all the braking he can), this rotor would be my 1st mod over braided lines.