Shock oil (use 25W ~ 35W with the tapered pistons below)
Diff oil (kit comes with 5,000 CST, can also try out 7,000 CST)

Updated diff o-rings (PN 89121)
10x1.1 tapered shock pistons (PN 89456)

Tires
Wheels
Pinions (I'd recommend Hot Bodies Mod 1 pinions)

You can use this as a starting point (other than the stock setup): http://teamassociated.com/pdf/cars_a...champ_2010.pdf