You cannot gear something for both, you should be able to find a ratio that makes you happy. If you gear it for low end or fast take-off, you will lose tope end. If you gear it for top end you will lose the low end. There are alot of variable you did not mention, engine size, and performance mods. If you want it to have faster top end than it does now, decrease the size of the sproket on the drive axle or increase the sproket on the motor. I would not do both at once, change one or the other. Go to you local go-cart shop they should be able to help.