Dold,
there are a few guys that are running 250's around my area, they are ok with power. they run in their own class. i run in the 500 class which is the outlaw class. single cylinder single carb, 550 cc max displacment. other than that spend spend spend. there are a few diffrent pipes being made, the one on the kart above i had custom hnd made from a snowmobile specialist in canada, spendy, pm me it you really want to know how much. it lasted one heat cycle(5 min) one hotlap session(3 min), and i flipped it in the next session. i had less than 10 min on the pipe and its pretty much junk. most of the guys are running CR 500's because theyare easier to find. ill put up more pics in a min here