I picked up an '09 CTS-V a few months ago with 39K miles on it, and now have approximately 42K and change. When should I expect to change out the brake pads? Any special procedure required? Do I also need to look at replacing the rotors? I'm just trying to find out if I can buy parts and do this with a very mechanically inclined buddy of mine, and how easy or difficult it would be. Note that I haven't tracked the vehicle and do not plan to, as this is a pure daily driver. Thanks!