As many of us discover when the snow gets really deep, a snowmobile can start to suffocate and have a hard time breathing, both in terms of intake and exhaust. Riding in a couple feet (or more) of fresh, light powder snow makes for great riding, but it really works the sleds hard. Air intakes plug, underhood heat levels skyrocket, and the exhaust might even try to cap off. This will all lead to the sled falling on its face (losing rpm) and not going as far as it was really capable of.
Some of the better fixes for this are:
1. Adding as much intake surface area as possible. High Flow intakes (like those sold by Starting Line Products) really help out here.
2. Venting the chassis for more cold air entrance and hot air escape. There are a lot of aftermarket manufactures that offer these kinds of similar kits. We have found this really helps, especially in these deep snow conditions.
3. Sealing the exhaust system at all of the joints and most importantly from the silencer outlet to the belly pan. If the rubber ring seal between the pipe and belly pan outlet is intact, many riders will seal it completely using high-temp silicone. We have found that (Permatex) Ultra-Black works best for this. It seems like we tell you about this most every year, but deep snow riders who fail to seal their exhaust system up will be drawing exhaust gasses into the airbox, especially when the intake starts to plug. In turn, the sled will fall flat on its face because there is no oxygen in the exhausted air. The number of mountain riders who fail to perform this step each season is huge.