Nate, I dont know if this will help, but, I ride with a guy who has an 06 mxz fan cooled, must be 550, he weighs about 225 230 lbs, and is 43. He handle that sled like its his own foot or something. I was riding my '98 670 Z last year with him and I was getting beaten after 50-75 miles of club groomed trails. Not him, and in late March on hard pack and ice when it got warm 40-45f I was running near sometimes in red but that fan cooled eng. never missed a beat. Great sled, light weight, great power to weight ratio. Good Luck