I have a friend with a 2002 efi mountain cat 800, it has been at the dealer quite some time and they cannot figure out why his sled wont rev past 6000 rpm's. I have it in my garage right now and i messed with it a little and when it hits 6000 it sputters and backfires. If you are familiar with the yamaha t.o.r.s it sounds like that. The dealership tried everything from a new wiring harness, cdi, power valves, stator, fuel injectors, went through the complete efi system. Anyone have an idea would be super helpful. thanks