I installed Miata seats in my GT6 and immediately discovered they did not fit properly. The Miata seat sits rather high in the Spit/GT6 cockpit (about 3 inches higher, measured from my seated butt to the floor pans) and takes away valuable legroom. Simply not an option for folks taller than about 5'10" or so. The Miata seat width, though wider than the GT6 highback seat, is okay.
However, the TR6 has a roomier cockpit and you may find the Miata seat practicable. At any rate, it will most certainly not fit like the stock TR6 chairs. And obviously, Miata seats were not an option on TR6s, I don't think /ubbthreads/images/graemlins/rolleyes.gif
If you dig a bit you'll probably find another TR6 enthusiast who's done the Miata seats, I'd assume such an opinion would be most helpful.
Anyone here?
Good luck!