Your KE will be about the same with different arrow choices. If you want to shoot a Gold Tip arrow that weighs 400 grains, you will still get about 70 KE. You cannot change KE by changing the arrow weight. You need to increase or decrease speed, but you cannot change the arrow. You will get more KE by increasing your draw length and you draw weight, and less by decreasing your draw length and your draw weight, not by changing your arrow weight.