Too many variables to say what is happening for sure, but I'll tell you my setup that hits hard on bottom. Big hub impeller (I'm running the hooker), 3mm milled off stock head, FP limited, msd enhancer (back to back from stock cdi I noticed very little if any difference though), sbn 42 or 44 can't remember. I'm actually running dual 44 blackjacks now, but mikuni hit as hard (haven't tuned new carbs yet though), very light porting (matching ports/gaskets/manifolds. *Except* for the crazy built strokers my sx hits harder on the *very bottom* than any other ski i've ridden (yes square or round nose yami's too) to date.