When you make more power you can go bigger on the weights all my modded bikes are running stock or heavier now,Another thing that dont sound right,but im running a 10g now on the hot rod,Im giving up alot of take off at the moment,but can cruise pegged at 1/8 throttle,threw an 8.5g in before trip and struggeled to get 60(pegged).Once again getting it all to work together is the trick.I don't have it yet either,my belt was still slipping a bit with the 9g 9.5 next or more spring fun or make the 10g work!!!