Hey fellas the CT5 and 4 already have the tallest final gear ratio on the market. If you want to increase rate of acceleration and top-end speed just put a race quality .21 onroad motor on the chassis. The .21 with its increase in torque and horsepower should make the ct5 accelerate alot faster and gain some mph on the topend. The motors I am talking about are the Novarossi onroad engines.