just got a hmf slip on for my 07 450er it runs great untill i get to high rpm seems like it starts to bogg but im not hitting the rev limiter. i put the supplied 168 main jet. now does this mean its to lean or rich. or should i go to a 170 main? or should i adjust the needle clip if so which way up or down?? thanks i have a race saterday so i need this to be tuned topnotch