Honestly the car really doesn't need anything at all beyond the servo horn. Most of us run the stock spring on 80% of tracks anyway, so you're good there. Besides the aluminum horn, I would pickup some 6x1.5 pistons, the low profile wingmount, and delrin shock guides and your car will be as tricked out as any team drivers car. I also like the low roll center plate or the new hingepin plates that take the square inserts, but those are not necessary to win races