Huh, I never saw this thread back when it started. In Sept, on my GTS I was running a full 30 minute session at the track and boiled the brake fluid I had in it (wildwood 570 and an a good front pad). The next time I drove the car I had what I called a groan in the brakes. I can even fell it a wee bit in the pedal if I really pay attention....drives me friggin crazy and I swear it was coming from the passenger side. So now every time I go out, I am on and off the brakes in neutral to try and figure out WTH is causing the groaning.

I did some poking around and couldn't find anything that stood out as looking unusual. However, I never pulled the pads, but will next time I have the wheels off. Then clean up the rotors and see if that helps.