Modernize Stock GT seats?

[azopelnut]

I would like to retain the stock GT seats but want to know:
1) What is the type or name of the foam rubber found in modern bucket seats? ...it seems much firmer.
2) Has anyone inserted/attached an aftermarket lumbar support into the padding behind the fabric with success?
3) Has anyone inserted speakers into a GT seat (as in a Fiero or Miata)?

[GTJIM]

I think the modern foam is known as 'closed-cell Urethane' which has various ranges of firmness.

It is firmer than the old Latex stuff and being closed-cell does not soak up water. Lots better!

I have a set of Impulse Turbo seats (in my 1984 Isuzu Piazza - too big for a GT) that have a nice, adjustable lumbar support that is really good. You may find that you can 'scavenge' the set-up from some other seat to make your GT ones similar.