A guy i ride with have a 09 Polaris Assault 800 with a series 5.1 (2.4" x 146") track. We do lots of river and lake riding but we don't have that much snow this year. Last weekend we went for a ride on a river and their was a guy with a 10 Polaris Dragon RMK 155" completely stock with us. The RMK was at least 10 mph faster than the Assault and it have a longer track. We check and they seem to have the same setup as far as clutch and gearing except the Assault have 1 tooth bigger on the top sprocket. Their was also two 2010 Polaris Assault with us (one with the stock track and the other one with a Camoplast Cobra 1.375" track) and they were also slower than the RMK. Is their something different with those Assault compare to the RMK??? Also I tried the 09 Assault and the low end is good until around 50 mph and it fall flat after that. The guy just bought the sled and he is not really happy about it. The RPM is always around 8200-8300. What can be done to gain some top speed on those Assault??? They don't expect to go 100mph with that but it should at least do 85mph. Any help will be appreciated. Thanks