So here's my idea for improving Thundertron's neck.
The head sits on a platform that rotates from the back and rides along a pair of tracks in the front. What he needs to let get that head up a little higher is for those tracks to be extended. His robot head pops right off, but his Lion head is sort of a pain to takeoff without breaking anything, so I ended up just angling in my power drill and using it as a router to cut through the plastic sideways, then doing clean up with my exacto knife. The best way to do this would be to take everything apart and work on the tracks with my drill at a perfect 90 degree angle, but things being as they are, the job can be done with a drill at an angle, or slowly with a knife. The good news is that the pegs don't go all the way to the back of the tracks, so you can get away with not drilling them as deep as they go.

The other thing I did, was to scoop out about a millimeter of material from the front of Thundertron' front collar/ lion head. It isn't that noticeable in Lion Mode and it lets us see just a little more of that big big beard. And speaking only for myself, that's what I'm here for. The the Lion Mode is, frankly, a bit crap. The Beard on the other hand, is magnificent. Along with the neck mod, this lets him angle his head further back and frees up more poseability options.

The next thing I plan to do for Thundertron here is to give him a top to bottom paint detailing to take that baby blue down a bit darker. I'm also building him a new sword. I would have used the blade from his springy weapon arm thing, but I find it too much fun to play with- silly as it may be.