If you want to improve your lap time the best money spent is Eric’s moto cross school. I know I have bought every trick part available and class time with Eric and his instructors has done far more than any aftermarket part.
I have taken classes from many schools and what makes this one stand out is that Eric is in your face. You get instant feed back and constant attention. The techniques that you take away from the school may save your life. Eric can teach you to jump doubles and if you are brave triples without killing yourself!