I have a RK-Tek head for a 1M 800 Arctic Cat. I has two sets of domes. One set for low altitude and a set for 8000ft and above. Has about 1100 miles on the head and high altitude domes. Low altitude domes haven't been used. Still in great shape, no dings or damage on any piece. The best mod for a 800 Arctic Cat, no fuel controller needed. 91 octain at altitude. Sold the sled need to sell it. $275 shipped to the lower 48.