Im thinking of changing mine as well, I have managed to borrow from a friend a few options but im yet to get around to trying for fit yet, they are Mazda RX8 , MX5, Smart Fortwo and a computer race style gaming chair!!!.
I like the RX8 but ive a feeling they're to big (wide). The Smart seats look as they will fit and MX5 are popular in many kits, not sure about the gaming chair, its very comfortable and well supported it would be just how to fix runners to it
Will be watching this thread for more ideas.
I also wondered about the airbags in the side of the seats