Megamax 2 Jetting

[Buzzsaw]

What is the best size main jet for a 300ex with this pipe?

[2K1 300EX]

I have the same question. I have the MegaMax II with the oversized header, uni air filter, choke removed, and 2"x2" holein air box lid. The cycle shop said I need a 135 main jet but I am not for sure.....I have been trying to find some more info. Any advice will help.Thanks.