Bore size
The actual piston weight difference between a standard bore and a 0.030 is negligible. That is if you use the same type piston. If you are going from a cast to a forged piston, you will usually add weight. I personally believe the added strength is worth the weight. The added power comes from more capacity , more power. Just boring the engine will boost the compression alittle also. The volume of the cylinder is larger but the head volume stays the same, so the compression will be greater. There's the old saying, "When in doubt, punch it out".