What do you plan to do with it, speed runs, bashing with big jumps, general off road with just small jumps?
---------- Post added at 8:12 PM ---------- Previous post was at 8:08 PM ----------
I'd get RPM arms, shock towers and front bumper. Traxxas big bore shocks, the drive shafts that I mentioned before, better tires, 2.4ghz radio and better servos. If you get the 3.3, grab the exhaust from a Jato. Convert it to the electric front axles, this will give you more wheel options as well as allow you to rotate tires as they wear down.