the wheel/tire weight has a big effect on speed.. with my old 750 std bore kit i could only get around 78mph with ITP ss112 wheels and terracross 25" tires.. i put the stock wheels and tires on and i hit 80, then after i realized i was in 4x4 and switched it to 2wd i hit 82mph.. rotating weight is a big power killer.. i should be in the low 90s now with the 820 kit, but i didnt get a top speed run in yet..