The Bikeman Performance billet head kits give you the best of both worlds with excellent horsepower gains and better cooling capacity. Our billet head kits utilize an improved squish band, new pocket design, and slightly more compression for pump gas friendly horsepower. High elevation heads can gain up to 20 lbs of compression. High altitude gains of 10 HP through the mid-range and 6-8 HP peak. Low altitude gains of 5 HP through the mid-range and 4-5 HP peak.