From The Archery Program, with Camo 5575 XT' s, 100gr. and vanes which would weigh 383 gr., on a FX 28" 65# you should be shooting 261.05 fps for 57.9 ft/lbs KE.

My Altitude shoots 250 fps with the same setup, 65# 28" , GT 5575 XT camo' s 100gr., and I consider it a relatively fast bow.