well, you can add anything to it you want BUT to race stock class you need a "stock" motor. so if you're going to race....then get the following
1. HPI F5 truck wheels front and back ( give ya way awesome wideness)
2. Tires to suit your track.
3. CA all your ball end's screw into the plastic( you'll pop them from there...trust me
4. get the right setup.