After two years my annoying chirp/squeak is finally solved! Up until today when I would shift into gear (auto), or back out of my garage, or hit a bump a certain way, there would be this high pitched chirp/ squeak from the rear passanger side of the car. It was always hard to tell if it was from inside or outside the car.

Finally, found the cause--exhaust pipe was moving and rubbing on a metal support bar which is mounted to the underside of the car. You can clearly see the area if you get down on the ground on the passanger side and look right in front of the rear wheel towards the center of the underside of the car.

It seems the rubber support of the exhaust pipe has sagged some allowing the pipe to rub the support bar causing the sound.

What I did was apply caulk (from the drivers side) between the hanger on the pipe and the support bar to limit the movement of the pipe. (proper fix I would suspect is to lift the pipe up higher and get it off the support bar)

Chirp/Squeak is gone....Finally!!!

 

You could also use a pipe clamp around the rubber support...but congrats on the find.