windage tray question

Drilling the main cap bolts is ill advised. While it is possible to do such things, can you do it yourself, the bolts are not an easy thing to drill and tap. also, can you afford to screw it up? The new bolts are not to much money and the best way to do such things.

On your build, even if mild, you can see a 10 HP gain no problem. I have seen several write up/dyno runs with 15+ HP gains. It isn't a lot and will never be felt, but each item you do for a few HP is worth the effort and will add up at the days end. Some here, some there, it adds up.