Tillett W1i (W2)
 

Has any one done or though of doing Tillett W1 type seats with a roll bar mounted head pad.

https://www.levelxms.com/tillett-w2-racing-seat

Can you see any disadvantages?

It will break your back in a rear-end collision.

really though, it had to come up just below the shoulders, they use them in caterhams a lot.

I feel that it would fit up against the rear shelf / roll bar like this. Then add a head rest mounted to the roll bar.

Yikes. NO.

0%

Tillett also makes nice fixed-back seats that are actually useful for cars and are super easy to fit in the Miata (narrow shell). Why not use one of those?

Price really, and I thought this was a neat idea.but I guess not