Hey guys, this is more or less my first serious attempt at a replay.

I really want to decap Uke with the punch at the beginning but I can't get enough power to do so.

Any help would be appreciated.

Try to pawnch Uke's chin, it is easier to decap him that way, or if you aim well enough, pawnch his neck, I managed to decap him in 1 minute that way.

To be honest. It's not really the best way to set up for a punch. You'd be better off slapping his face off instead of punching.
But, you need to get your aim down just right before you even attempt to 'punch' uke. Your timing was off, and it didn't look like you were full of momentum. You probably already know this, but it's called the spider technique. Left rotate chest, extend left pec, contract right, same with legs. If left pec is extend, left leg is extend. It's used for gathering momentum and gaining speed. Using it correctly will result in speeds above 40 easily.

And remember, lumbar moves your punches left and right for aiming. Abs makes it go higher and lower. The head can be used for aiming high and low as well.
Contracting your wrists when you contract your elbow, results in bending of the arm faster. And when you extend, extend the elbow first and than use your wrist after a while to maximize your punch and have it deal a stronger amount, resulting in a stronger looking decap/dismember.

Hope this helps ;)

Alright, cheers Hacks.

I'll give it a shot.