The clutch heat is my main concern. I have a 154 2.5" and have not blown a belt, but my clutches are hot all the time no matter what I am in. Deep snow or on the trails. This past weekend my brother in law and i went sledding. He has a rmk pro. We were climbing the same hills and when we got to the bottom I checked his and my clutches. My primary was scalding hot. Secondary I could hold onto but it was hot. Pro primary had almost zero heat and secondary was a little warm. He added a lot of venting which I am sure helps a little. I took off all of the plastic shroud and it helps but not a lot. Other than that I love this sled.