Yes we all know how to use polar-to rectangular inversion to get a normal mapping at the top of the head. But what Darkjak means is a glitch in TB 3.8 where the top of the head become a pixelated triangle. (At least that is what I think he is talking about...)
I do allso work in 256x256 resolution, and then i size it down to 128.
Think about it: 128x128 is 1/4 of 256x256!
If the default head-texture resolution was 256, I would be happy.
Inorite?
I mean, it makes a huge difference when you have 4x the pixels.
Have you tried uploading the image so that others could see the texture, but saving the texture in your folder yourself in 256x256 and marking it as read-only?
It should work and it'd be a good compromise.