Originally Posted by grippgoat

Basically everyone runs 50mm front (or 51mm if they choose Spec-R / RSD... I run Spec-R and like them), and kit 52mm rear. Drive shaft length is the kind of thing you mess with if you're Hagberg trying to dial in the last tenth for some obscure track / tire combination. Xray has done the testing for general use, and the answer is 50mm front / 52mm rear, which is what comes in the kit.

-Mike