C50 Owners

[350TacoZilla]

The 2 speed rear you would want has 7.95:1 low and 5.83:1 high range so you would have better off line power and higher cruising speed at same rpm as current 7.2:1. Looking at numbers online they also made a 8.72:1-6.4:1 rear but that wouldnt help your rpm as much. a 2 speed trans behind current 4 speed is also a option if you can find one.

RPM difference with the 7.2:1 to the 5.83:1 is around 600rpm @45mph and 800@65.

If your only after a few rpm drop and are happy with off the line power then you might be able to just step tire size up a bit.