They look really good. Not sure if you are looking for feedback, but the only suggestion I would have is consider turning the bolts around so the head of the bolt is where the locknut currently is inside the seat. It looks like the threads and the locknuts stick out quite a bit further than just the head of the bolt would stick out and they could end up wearing a hole in the seat cover or even make contact with the helmet too. Just a thought.
Either way, looks like a good head restraint system.