It's a competition car, no upgrades are needed or available. Only tuning options. If you don't have them already, here's a list of options you should have...

Different weights of silicon oil for shocks and diffs
Different spring sets for shocks
Different gear sets (pinions/spurs) for changing ratio
Differential options (front solid, front one-way, rear solid)
Different strengths of anti roll bars
Clutch options

Instead of looking to hop up a car that doesn't need hop ups, spend your money on good radio gear and a better engine and pipe.

Nice car, I used to have one, enjoy the build and take it slow. Good luck.