I was wondering how would 20/41 chain-case sprockets work for more top end.right now it has 19/43 and tops out at 70mph on speedo.or should i just change the 19 to a 20 and leave the bottom sprocket?any clutch changes needed?the races start next week.gonna try out the fan-cooled cross country.oh it's a 2008 RMK 550.LOL.any info appreciated.