If you get yourarrow weight along with your speedyou cancheck the easton or goldtip site to get your KE. If I am not mistaken you need atleast 50#'s to go with mech heads. If I am wrong someone will correct me so don't quote me on it. The spitfire has a large cutting diameter and may be to much for your set up. No doubt they are a great head but there is also plenty of heads out that will work for you.