Are u racing offroad or onroad with it? For onroad racing all you really need is oil shocks, foam tires, better motor, and some decent packs. For offroad I would suggest the same except for instead of foams just make sure your tires are in decent shape, the stock ones would probably work OK.
I'd try posting this in the mini and micro forum tho. They may be a little more helpful.
RCAmerica/Xray <> Panther <> RW Mods