For every inch of draw length you go down you will lose 10 FPS

For every 5# draw weight you go down you will lose 10 FPS

For every 3 grains of weight your arrow is over IBO you will lose 1 FPS

For every 3 grains of weight you add to your string you will lose 1 FPS.

So I would guess about 273 on the head. It could shoot a little slower it seems like they always do.