Does any one know what gearing i should run at Road America i have a 2008 Gsxr 750 and currently have a 520 chain with 15 front and 47 rear sprocket stock internals. I would like to only change the rear what would you suggest.

No idea what that is (-1 or +1 or whatever) stock but that's what I would run. I'm on a 1000 however but even at Road Atlanta most 600's run stock on the rear with -1 up front. You have quite a while to build up steam up there!

yea with the 520 kit from stock im -2 in front and +2 rear works great at Blackhawk farms but thats a lot smaller track lol from what i have seen it looks like i have to go a 43 or 44 in the rear so my top speed should be arount 159-163ish

Im on a 1000 and still have a lot left in 6th, I can actually wind out 5th all the way to my braking point if i screw up the drive on the last turn. :D Thats just +1 on the back.

^for sure on the middle and the front. I have never (even at Road Atlanta) been able to wind through all the gears. I remember thinking on those two sections if it was a good thing to hold it close to the rev limit for so long :) That was after my nap and light snack before the turns!

Great thanks to get the same/close ratio to keep my 15 front id have to run 43 rear. so if the 1000 are not hitting 6th looks like i might want a 44.