I’ve put in all the available CS kits I have in the market mainly for Yokomo shaft driven. The internal ratio ranges from 3.308 to 1.176. The standard internal drive for Yokomo is 2.353.

To understand the graph better, bare in mind that anything higher than 2.353, the tires will be slower, and anything lower than 2.353, tires will be faster. If we need the rear tires to spin fastest, Yokomo 2.0 is the choice (claimed to be 2 turns faster than the front tires and meant for high grip surface). If we need the rear tires to turn slower than the Yokomo 2.0, we have an option of getting the Yokomo 1.5, Kazama or Active Hobby 1. Apparently Yokomo 1.5, Kazama & Active hobby 1 have ratios close to each other (probably all of them have already discovered that internal ratios between 1.588 and 1.85 is the best for CS?). On the other side, the Active Hobby 2 has a higher internal ratio from the standard, meaning the wheels will turn slower instead of faster, this ratio is meant for the fronts.

So basically if you have all the ratios, you could mix & math which one suits you, your car and road surface. If short of cash, personally I would go for Yokomo 2.0 & Active Hobby 1 together to have it balance. Otherwise, if you have to choose one, I’d go any of these three kit; Yokomo 1.5, Kazama & Active hobby 1.

 Good luck!