I read a while ago about an easy seat mod that people over on iwsti were performing. I'm not sure if this is applicable to WRXs or not - excuse the ignorance.
Basically, you unzip your seat and undo 3 clips that hold a horizontal wire 'support grid' across the two vertical seat supports. This allows you to comfortably use the seat material and vertical supports to sink back into the seat more. You have more side bolster, and it does not appear to stress the seat (provided you carefully tape over the hooks when unhooked). Some people were fancy and took the whole grid out, some bent the thing and put it back in to make a more 'custom' fit seat.
So my lower back has always gotten a bit sore when driving my STi. My genetics tend to have some rather unflattering extra 'cushion for the pushin' in the back. I think this combined with the rather firm support in the wrong place in the stock seats causes the slightly muscle strain.
This past weekend, long story short, I ran into a slight episode of medium leg pain and minor pain above one side of my butt. I have a doctors appointment scheduled on Monday, and it's liveable until then. Just muscle tightness/soreness now. I'm not blaming the STi by any means, but I think I might give this mod a go and see how it feels.
Has anybody here done this? I don't know how this mod plays nicely with larger 'behinds'. I'm about 5'9" and 175 (in a heavy phase.. normally about 155) for reference. Looking for any experience with it. Even though it's reversible, I don't like to mess with things on my new car that aren't 'broken' (*cough, holes in bushings, *cough).