07 rhino 660, 27" duro tires on ITP rims. Machine has 6500 miles on it just got it today. Took a drive as soon as I got it home, 33mph hit limiter on flat ground with GPS on phone. Brought in shop, changed clutch sheave and purple spring on secondary clutch. Did nothing else except clean clutch and belt and installed new parts from Hunter works. Same stretch of road same amount of of distance hot 44mph on GPS on my phone at limiter, can peddle a bit and get 45 . I'm not surprised tho, did clutch work on my 660 grizzly and it was amazing. Have a dynatek CDI on the way and a cold air intake for this machine , hoping to comfortably run 50mph and still have peddle left. I will probably get some lighter tires very soon also.