rmitch1

The CT4S has a very tall ratio, to let it reach very high speeds. The CT4R is set up for track racing. The difference is in the belts and pulleys. If you are looking for more power out of the hole, you may want to consider getting the CT4R pulleys and belts. Its only three part #'s. I will list them below. You will notice a considerable difference, with minimal top end lost. Ive seen people take the CT4S and put a .21 racing engine in it. I clocked it at 94mph at the Anaheim Edison Field.

CT019 main belt
CT015 16T pulleys
CT011 Rear belt