couldn't tell you how much but i could tell you that its probably not needed for any hunting or target shooting situation. you would probably gain both speed and KE. I think it would be tougher on yourself for what its worth. i think extending your draw length gives you more speed than going with heavier poundage but its pointless to extend draw length because its just harder to be consistent. i dont know any ballistic calcs of the top of my head but if you type in arrow speed calculator on google i'm sure you'll find something. Hope you find what your looking for, i'm sure many others on here will be able to help you too.