monkeyracing,

Ball Diff: I build as per instructions and use lots of tamiya anti wear grease, this will make the diff very smooth. As Defmondo pointed out, do not over tighten otherwise you will strip the diff. Some people also insert an extra cone washer to make it a little tighter, however that may go against your TCS rules.

Gear Diff: Add thicker washers to each side of the diff, or if you have extras add a second washer to each side. The costly way to make the action stiffer is to pack with tamiya anti wear grease, however this loosens up after a short time. Just use the kit supplied as a guide for size. Whem you get new bevel gears for the diff, normally has replacement washers with it.

SERVO SAVER: I have recently fitted the Tamiya M-Chassis Aluminum Horn and Hi Torque servo saver to my Mini and it works great. It is the same as the kit supplied plastic horn in alloy and uses the Hi torque servo parts and springs. This will give the same throw as the original, but is now stronger.

When you use smaller servo's and servo savers you end up affecting your steering on the car. I use a full size digital servo. I have found that the plastic servo posts are better replaced with alloy posts. This limits the amount of flex when turning the steering lock to lock. Some also have four mounting screws for the servo, which gives more rigidity to the assembly.

Just my thoughts.

Calvin.