Remember (I don't remember the formula) that KE = weight * Speed and there is a constant there so 45# KE should perform to the same level all things considered and if there is a difference it will be the heavier arrow that penetrates further due to the momentium carried.
Remember back to physics and all those equasions and formulas. Here is where they come into play.
Again I don't have access to the readily right now.
Greg
"Getting close to the game is the joy of Bowhunting for me, the harvest is a bonus."
Live 15 ft Python after eating a small Antelope!