Jeff:
At least what Teemu (and I) are running is that you place thin shim plates under the upper bulkheads. The diffs are not raised, but the upper wishbone mounting locations and the shock towers are raised.
My latest mod:
I've machined a 19t pulley as the 20t pulley made the rear belt so tight. It's running super free now! I haven't track tested it yet as the pulley needs to be anodized before that. I don't know if it will take the torque of a mod motor, but it probably is a hot ticket at least in the 19turn spec class. By holding the wheels and turning the spur it is very difficult though to make the belt skip. The diameter of the pulley is 16.36 mm kaming it 0.89 mm smaller than the 20t aluminum one in diameter which is 17.27 mm when new.
I wonder how much is it possible to make a 20t pulley smaller or a 19t pulley larger without running into problems with noise or efficiency. I remember when the first Cat 2000 prototype came for JukkaS it had three different tightness rear belts supplied with it all with the same tooth count, so some playing around is possible.
Adjustable layshaft mounts are also under consideration if anyone has a clever idea how to make them.
BR/ JesseT