Look online for a gear chart. There are tons of them floating around. You compare tire size with gear ratio and inside the matrix is RPM. I think there is also a gear ratio calculator here on either the PHP website or the PHP forum. I just went through the Pegasus program (for my programmer), which has a gear ratio calculator. Using 235/70-17 as your stock tire size and 315/75-17 (approx. 35" diameter), the 4.10 would bring you similar to the 3.55 stock ratio. 4.46 would be ideal to get you to a 3.73 ratio but the next closest gear option would be the 4.56.
The CS/CTS do not have the datalogging. I was thinking you had the MC gryphon for some reason.
