If you calculate the numbers on the arrows that I posted you can see that my numbers agree with MeanV's findings. All three arrows were shot three times eachthrough the same chronograph, out of the same bow, at the same draw length, at the same draw weight.

For poops and giggles I just shot a 397 grain arrow too.

397 grain arrow... 315 fps ......... 87# KE
443 grain arrow...302 fps ......... 90# KE
502 grain arrow...283 fps ......... 89# KE
625 grain arrow... 256 fps ......... 91# KE

Aparantly the 82nd, and probably the 101st, are less efficient with certain weight arrows.