This is a must have for all xp owners riding in the steep and deep. Under prolonged continuous wot riding you will experience power fade. This billet housing replaces the stock thermostat housing. The stock thermostat doesn’t open completely until the engine reaches 150 deg. At 145deg. the computer will start to retard the timing (built in safety to keep the motor from burning up) and will rob you of up to 10hp. The thermostat in our housing will be fully opened and close off the bypass circuits at 120 deg.(optimum 2 stroke operating temp.) The stock thermostat housing flows 26.1 liters per min. Our billet thermostat flows 33.5 liters per min. Your engine will run cooler and make max hp. all day long. This will prolong the life of your piston rings and greatly reduce the chance of engine failure due to heat stressed, flaking piston rings. This is one of the best upgrades for the xp and you WILL notice the difference in the deep snow. We strongly recommend this product when adding a billet head with higher than stock compression ratio or when adding a turbo. Thermostat and hose clamps included.