50k worth of mods was it? for an extra 20k? and that's when it was new - probably only 7-10k difference second hand, definately seems worth it.
Seeing as I've already spent $$$ on rims, springs, exhaust, then tuning next, shiiiiiit, the dollars spent is getting close to that price difference already and I haven't really done shit. I still have poxy brakes and a 5sp transmission (the gear box alone must be about 6-7k eh??). That sti is looking mighty good right now.



Take a look at this website

http://www.cars101.com/subaru/impreza/wrxsti2005.html

This is an UNOFFICIAL specs page for the 2005 wrx's. (other years listed too)
I don't know how accurate it is, but it does list a lot of differences between the two.