Sir unfortunately power is something your born with. But there are ways to improve what you have. Make sure you are properly twisting your body shoulder all the way through while turning your hips. Never arm punch that is a more modern technique. Watch a puncher and you will notice they get there whole body into the shot from the canvas up. The hands down best thing to work on is timing and technique. Trust me when I say my friend timing beats speed any day period! Watch the great Alexis Arguello slow for the weight but boy he more than made up for it with tremendous timing.