Taking the 501x Racing: What Options?

[TRF_AK]

Ok like the title says, I am taking the 501x racing, and as this is the original and not the Worlds Edition, what option parts do you feel should be purchased for racing? There are so many parts from aluminum steering parts, caster blocks, etc. Let me know what items are higher up on the list, and which parts are a bit lower or the "nice to have".