how do you do powerful punches that can maybe blast a bodypart or 2?

It's all about speed and timing. And off-topic is the wrong place for this.

You also have to incorporate many body parts, like the wrists, elbows, shoulders, pecs, chest, hips, abs, and ankles.

Also once you have the speed and timing down, try to ghost through uke (which is very hard when punching) but you'll most likely hit a lovely boom hit.

Also go to your default replays (if you still have them) and watch Larfen's What have I become replay. It shows how he builds up power and gets an amazing boom with a single punch.

Practice makes perfect!