[HammerZ]

Most Mini-Zers like to work on the handling first and make it fast second. You may go with a faster motor but these things are known to be fast out of the box already. A number of Zers like to try softer tires first to get it to hook up.

The ball diff is a big improvement over the stock plastic gear diff. I have been known in the past to put a hot motor on a stock Z and it can handle it. it is very hard to control. The stock diff is known for wheel hop. The ball diff can make it more controlable with a faster motor.

Bearings, the MZR shop sells some nice bearings. In fact they stock two types, Dry and Enduro. The Enduro is cheaper but need to be oiled, but the dry is worth the extra cost and if you buy your readyset from the shop some come with the dry bearings for free. I have seen worst bearings on the market for Mini-Z's than these.