The head on the KBB upscaled New Age Bumblebee was disappointing for many, and some people suggested swapping the head with the Titans return figure or the the Mecha Planet one.
I had some time on my hand so i decided to try with a Big Yellow Bee i got for cheap, here's the result:

This modification is reversible for the KBB figure but not for the Mech Planet one.

If you're interested here's what i did:
1. Remove the head on the KBB body
2. Unscrew the head on the Mech Planet
3. Remove all the extra plastic for the screw inside to make room for the new balljoint
4. Carefully reattach the two halves of the head with loctite
5. Fill the inside of the head with all purpose glue
6. Pop the head on and let it rest for a night or two
7. Remove the extra hardened glue that spilled out and try to move the head
Extra 8. I also cut the head of the old screw and glued it in the empty hole behind the new head, but you can fill it however you like.