98 tcat mc 136x2 stock except for clutching 20-39 gears [mine] 02 mxz 800 stock 121x1.5 [kids] 20deg F today and the 2 sleds ran side by side in a 1/4 mile run 12 inches powder. not impressed. book calls for 410 jets @ 2500 feet.i have ben running 400. i sure notice hp loss as temp goes up and plugs are dark. is the book close or should i be a lot leaner. we can't run wot like most of you guy because of our terrian so not much chance of burning a piston [ i hope ]. also considering 24-39 gears.