Another update:

-I have disassembled the entire center arm rest and removed it, nothing loose in there, noise still there.
-Tried driving without the rear headrests, noise still there.

The weird thing is, when I fold either rear seat down, doesnt matter if it's both at the same time, or one or the other, the noise is gone. So what the hell?

I really don't know what else I can do!

 

Ok so im not sure if i have the exact problem but i have a 2005 B6 a4 quattro and ive noticed now that its cold out im getting a chirp/rattle in the rear. its so damn annoying and its when i go over any little bumps? and now im getting it in the front of my windshield too. so im thinking it might have to do with the wind shield or something? has anyone else had this problem? but maybe check that.

 

the rubber trim around the sunroof makes chirps and squeaks and many times you cant tell the sound is coming from there. It can sound like its in the back or the front.

Drove me crazy for a long time until someone told me a little grease on the rubber and the sound was gone.

Also the the piece of plastic where the sunroof dial and map lights are have known to make noises that makes it sound like the back seats are making noise when in fact they are not. Try pushing on that thing when going over bumps and see if you notice a difference.

 

So after months of turmoil, sweet merciful crap it appears I've finally fixed it!

A couple guys on the Audizine website had the same prob, and here is what it was for anyone else reading this:

You have to remove the rear seats entirely and wrap the pivot pin on each side in very thin fabric tape, I used electrical tape because my felt tape was a bit too thick.

Reference pic:


-So to take out the rear seats, fold them down, and in the middle, right between them there's a plastic piece (item #32) that pops off exposing a hex nut

-Remove the hex nut and a metal piece will come out too (item #31)

-Now with the seat backs still down, from the middle where they both meet, note that you can lift the inner ends out:

(pic is from an avant but you get the idea)

-With one end lifted up and out, you can now grip the far end of it and pull it, it will slide off the pivot pin (item #28 )


-The pin that is attached to the car is now exposed, this is where the tape goes, one layer as thin as possible will do

-It should not be difficult to put the seat back on this pin. If it is, the tape is too thick

Once that's done on both sides, put items #31 and #32 back along with the hex bolt and that should solve the squeak!

Doing all the other stuff I listed in my prior posts, I believe it helped cut down the smaller squeaks and rattles back there, but this was by far the main one.

Hopefully this helps someone else too.

 

Thanks Phat J, beauty post.

 

so i found the annoying little chirp/tweet rattle sound. there was actually two spots its making sounds. first spot was actually rite in my srs steering wheel airbag cover. If i pull on it i bit towards me it goes away, and the second spot was on the driver side rear panel where the seat belt comes out. so im going to address them this week sometime, and ill post the outcome.