On the diff cams- in order to not bind the bearings, we toleranced them to leave about a 0.2 mm gap with the upper arm mounts. This gives a little bit of play that we eliminate by using some body foam spacer tape, 1mm thick. This compresses when you tighten the upper arm mount and eliminates the slop without binding the bearings. We found this to be a trick that frees upbthe drive train further and has a "dampening" effect on the drivetrain. To me, the car rolled freer through the corners and it translated into more corner speed.