inline6power

ok i am a huge bow hunter and i am have a serious debate on kinetic energy with compound bows. i have a few people that may be right that i am argueing with. here is my question. i am shooting a compound bow at 72 lbs of draw force, the arrow weight is 415 grains and the velocity is 337fps. i am calculating my kinetic energy at 100.4 ke. now here is my question and the debate. i have a few people telling me that now matter what, if i go to a heavier arrow weight, that means that my ke will go up no matter what. i beg to differ unless i am re tarded. if i take a 650 grain arrow and shoot it threw the same bow, same draw force of 72lbs and the arrow is flying at 259.5 fps , my new ke is calculated at 97.2 i know their are alot of varieabls with arrows such as arrow spine, how stiff, carbon or aluminum, and how effecient the bow is. as weight goes up , the more effecient the bow becomes. my next question is there a middle ground where mass will go up, velocity will go down, and ke start to go down? take this for a comparison 415 grains at 337fps is 100.4 ke 650 grains at 259fps is 97.2 ke. the real debate is alot of people say ke is king and that the heavier arrow will always have more penetration than the fast lighter arrow and i think they are wrong. can you guys help me out a little? any one? come on someone has to have some answers for me lol. thanks in advance come on lol i know some of you guys must have some answers. i have a big debate going on another forum as we speak lol. just looking for more info on the questions at large.