Originally Posted by Leester

Check out posts #1156 and #1187 for information on how I lightened my drive train. There is an 11 gram difference between a Tamiya gear diff 25 grams and a ball diff 14 grams. There are additional things you can do to lighten the drive train significantly and are mentioned in the posts above. There is also a video in post #1187 that demonstrates how quickly this car rotates and accelerates out of the corners. The lightened drive train also allows you to drive deeper into the corners and brake later.
Maintenance of the ball diff running stock (17.5 or 13.5) is about the same as refilling your leaky gear diff