I did the "DIY Seat Mod" from IWSTI on Monday. Here is the link:
Basically just unhook or remove the spring/wire/mesh from behind the back of the seat. It takes about 5 minutes to do. I completely removed the mesh from both front seats. You could also use "S" hooks to simply extend the mesh.
With the mesh completely removed you are able to sink about an inch further into the seat. This makes the seat bolsters hold you quite a bit more tightly. I never thought the WRX had enough bolstering, and this simple mod makes a big difference. Highly recommended!
Sorry no pictures. The seats look exactly the same afterward.