Short review: Jass Performance Seat Bolster reinforcement.
 

I don’t wanna be all miata.net like I’m talking about what trinket I picked up for an exorbitant price from Moss Motors, I actually didn’t do that, but I bought these a few weeks ago from Jass Performance and man I really like them and you will too. The difference is day and night; I feel like I am actually sitting inside the seat and not on top of it, opted to use both plates on the driver seat. These took a worn driver seat and returned them to working as they were intended to do...

If you autocross your car and want to greatly improve your oem seats, I recommend picking up a set of these.





https://cimg1.ibsrv.net/gimg/www.mia...a702c2f56.jpeg

Mind sharing your personal dimensions? Always helpful in gauging seat changes.