i'm running 30mm rs carbs i like them i have the portwork to go to a bigger carb, but actually in all honesty i'm satisfied with the lowend i get from using 30mm. and my pipes allow for the topend pull.. i think u should consider using rs carbs if u want the lowend and if u want more pull on top change your pipes up consider getting your flywheel lightned .. advancing your timing and porting your cages .. theres so many possibities u can do to increase your hp . right now my bike is nowhere near an mx bike but with my port, 30mmrs carbs , ported stock reed cages, timing advanced +4 deg. im at sea level and im right at a 370 main with the needle at the 3rd clip.. one thing to consider if u decide to get rs carbs is that u need a bigger pilot jet then u would with fs or ds carbs .