I have a 2000 400EX. It is going to have a Yoshi. slp on, K&N air filter, and rejetted shortly. What else would I need to do so that I could race it, because I would really like to get into racin?

2000 400EX

 

You can race it right now. I'm pretty sure to race though, you need nerfs and a number plate for MX. If it is MX and you want to get really serious, go for suspension stuff first. Shocks, A-arms, axle, and so on. Good luck.