Depending on your weight and riding style, you might get away with the stock springs on your GSXR. In that case, the valving would be the only thing left to change. But, as Brian suggested, be sure you spend some time talking with experienced suspension tuners to find out if the Race Tech Gold Valves are what you need. From what I understand, the three-port valves behave differently than the four-port stock valves, and can be more difficult to fine-tune.
Note: In 2001, our GSXR's used stock fork springs and pistons with custom valving. Our rider (145 lbs.) finished 7th in AMA 750SS and ~12th in AMA 600SS, earning LP Racing's Privateer of the Year award. Not bad for nearly-stock forks...
