It seems their are alot of issues with G6 brakes, let me help on what I've seen. I have a 2006 G6 with 36000 miles and the squealers started hitting the rotors on the back. I took it to a dealer to see if they would help and of course they tried to give me the shaft. While i was there I asked why the backs wore out and the fronts are still good, like 85% remaining. they told me it's because pontiac perportioned the brakes so the bake brakes would do most of the work, so i had to ask, then why did they put such a small rotor and pads in the back...crickets. I went ahead and changed the backs and noticed the calipers are floating, meaning the pads are not pulled off the rotors when you let off the brakes. If your rotors are warped then you will hear the chirp chirp when driving slow. what i did to fix the problem is grind the paint off the pads where the pads sit in the calipers, and applied anti-seaze. this way the pads will move away from the rotors when no pressure is applied. I also put some brake squeal stop on the back of the pads where the calipers touch. this kinda sticks the pads to the calipers. so far so good. One last thing I noticed was the back rotors are solid. these suck because they do not disipate heat, which will eventually lead to warpage. personally change it all out.