iv said it once and ill say it again.. 300ex shouldnt be a problem... i raced 2 piped and jetted 300ex's down the river when i first got my blaster and i walked away from them like nothing... i have no air box lid, jetted tuned carb, answer silencer, boysen reeds and vertex piston with the jugg cleaned up( light polish just to clean up casting imperfections) 13/40 gearing 22 inch tall rear tires, aftermarket clutch, and im 250 pounds and out ran them