Our mountain series billet heads bolt on some serious power for your Arctic Cat 800 motor. It is designed to run on premium pump gas when ran above 4000 ft altitude. Huge torque gains to provide the grunt you need and want for boon docking and climbing. Much quicker throttle response! 7-8 horsepower peak and 8-10 horsepower in the mid range! These heads work extremely well on this motor!