Was fitted this summer by Matt Bickford in Danvers Mass, with a 910 D2 10.5 Kai'li Reg flex, set on D1, good launch angle and low spin, club head speed 90. Results 225-235, very pleased. Stopped by Golfers Warehouse found a returned custom ordered 910 D2 10.5 with a UST Proforce V2 Regular flex, just had to try it. Results 240-250. The UST is 57 grams or 5 grams lighter than the Kai'l, my question is can shaft weight make that much of a difference? Will go back to the launch monitor to check launch, spin and club head speed.