ya know, considering what i have read on here im really surprised at how many of you say they are a must. When i got my first mountain sled this last fall i really thought i would need them to ride in the black hills. But even last weekend i rode in about 3-4inchs of pack TRAILS for at least an hour at a time for quite awhile and as long as i hopped off the trail for awhile i never really got hotter than 140. Then again that might be cuz i only weigh 145
I think it has as much to do with lubricating and cooling your hyfax as it does throwing snow on your heat exchanger. But, I use them, especially on any modded sled.