As soon as I got mine, I just stregthened all the frontal plastic parts. The front hinge pin holder...I broke mine second time out with it. I didn't put it on thought until I broke the plastic one...just to see how strong the plastic brace really was. It took a good few crashes and it was only an impact with a concrete slab at southport that broke it.
And the alloy front hubs. Not a necesary upgrade, but I just wanted peace of mind really. Other than those, nothing else really.

bloody good and quick car.