The higher the FOC percentage the easier it is for the fletchings to do their job.

My FOC percentage is almost 14% and my arrow weighs 497 grains.

It's not all that difficult getting a FOC up to about 12% if you aren't obsessed with shooting a 100 grain or lighter head just to pick up 5 fps. Honestly a 125 -130grain head will ballance the arrow much better than a 100 grain head unless you are shooting extremely light weight arrows like a youth would shoot.