There is a thread about these seats on the other mr2 board. Apparently, two people have stated they needed to take it to a professional shop to install it because they are about 3 inches too short in material.
Ref:
MR2 Owners Club Message Board™
Owner 1 comment: The shop is Don Elkins Auto Upholstery in Fairfax, VA. They are a full upholstery shop. I had asked them about making seat covers before. They said the seat bottom was about 3" short of fitting, so they are going to add extra material. Hopefully I can get some pics up for you guys to see how it came out.
Owner 2 comment: t's ok Dave, there was no way for any of us to know. Unfortunately the jerks at that company keep the ebay bidders names private so you can't even warn people about their poor fit. I will be having a shop modify mine to fit too. Mine are about 3" short as well.