This Performance Kit is a step up from our standard durability Fix Kit. If you want the dependability and proven track record MTNTK Performance has with more power, then this kit is for you. This kit produces a 8HP gain over stock with increased throttle response from the addition of our billet head domes. The all new MTNTK Performance Cheater Head with our billet domes is a must have for any snowmobile enthusiast looking to gain more horsepower and better throttle response without any fueling changes or additional engine modifications. Each head is machined to proper specs which results in perfect fitment. Domes are available in 13 to 1 compression ratio for compatibility with pump gas at all altitudes or 15 to 1 compression ratio for those who crave even more on higher octane fuel, just add a note or email us after placing the order if you plan on running race fuel or pump 91 octane fuel. Our performance kit is available for all '08-20 800 CFI Engines. This kit requires you to send in a core cylinder head, even if it has damage it will most likely be a usable core. Some applications may require heavier clutch weights to keep operating rpm in the correct range because this kit definitely makes some power!