I am shooting a 70lb bow and am wondering how much speed, approximately, I would loose by going to an approximately 48 grain increase in arrow weight? My 375 grain arrow now shoots at 285fps with 70lbs of K/E and am thinking about trying a 425 grain arrow and was wondering what the K/E would end up being with the speed decrease. I know this might seem a little petty, but I am just courious.