For sure. If I were doing my seats, at least the driver seat, I would have custom foam layering with a nice memory foam on top. I might just do my driver seat bottom since there’s an aftermarket vender selling a very comfortable replacement for $75 or so.

Miata or not, I’d never go with factory foam when there are much better materials out now. Even from scratch, any good upholster could carve one out by hand in no time.