I have searched the forums and only found one article in the FAQ as to how to change the rear brake setup.

It is not very descriptive, and I am having trouble figuring out how to remove the rear calipers.

Which bolts get removed? I'm pretty sure I know which two are being referred to, but none of my allen wrenches fit into the hole where the bolt should grab. Is it possible I have bigger than a 7mm hex bolt in there?

You do need to remove the calipers from the carriers. If doing rotors you also remove the caliper carrier.

G

push in the piston to free the caliper from the disc. I also don't remember the exact size of the allen key bolts but it's a common size. Once the piston is pushed in enough you can remove the caliper and if your discs are really worn get new ones, there isn't much excess provided to turn, I think Audi does this on purpose.
Here's the tool I use: http://www.metalnerd.com/cat08.htm

Good luck!

Ordered new calipers, rotors and ceramic pads to beef up the rear.

13mm bolts thread into the slide pins. You need a thin 15mm to hold the slide pin while removing the bolt. Get the caliper off and then you have more room to deal with the carrier.

What did the calipers and rotors cost new ? Have you already upgraded the fronts and the master cylinder to S6 ? ~ John Buchtenkirch

I could have gotten the rotors cheaper, but I wanted nicer ones.

Fronts are stock A6 as they're in good shape. I'm either going to do the A8 upgrade if my 15's will fit, else I'm just going to change the rotors to match the rears.

Master Cylinder is also stock.

I'll post a writeup with pics, all my sources and price comparison when I'm through.

Is there any trick to getting it loose other than using pure brut force?