from what I have seen while doing clutching changes..they run best at 82-8300 all stock, but, you have to watch out at 8300 if it unloads the track for any reason it can hit the rev limiter and bog..if it hits it hard enough it will turn on a check engine light and go into limp mode..also the guage doesnt react fast enough, on a good climb i unloaded the track, guage showed 8250 for a split second, sled hit the limiter and bogged, on the 3 min replay it showed 8450 when it bogged...adding 1 gram to the tips of the mtx's eliminated it from happening again...I honestly thing a lot of the bog issues guys are seeing are limiter related, even at 1/2 throttle on the trails, another setup I was trying was at 3500-4500 ft elevations, all stock clutching except for 64 gram bellybusters, sled running down the trail at about 20-25 mph would hit the limiter and bog every time I throttled it over 1/2 throttle,(only showing 7500 rpm on guage)I changed out to 66 gram belly busters and it stopped hitting the limiter and bogging, but sled wasnt near as snappy as it was with the 64's............