Actually, we should apologize for missing out on a round of applause for you in the first place!
 

That is one outstanding project and research job well done; the more details the better are people off in their attempt for any DIY's on that subject......keep 'em coming ;-)

Hey a lot of that looks familiar =) Still working on a possible 355x32mm rotor
 

solution as well.

I've been traveling a lot the past month and haven't had a chance to mock up my cayenne brakes yet, but stay tuned!!

Thanks again for the info. and all of the emails back and forth Bob!!

5x130mm bolt pattern.

I agree, I know that I can always learn something new in Bob's posts:)

How about putting some of this energy into investigating...
 

rear Cayenne caliper fitment on ar's. They're e-brake compatible and match the fronts(gives thumbs up).

Haha already thinking about something for the rears. I have new S8 rotors and s4 calipers waiting
 

but I may see if I can get something bigger to fit =)

I can do that...
 

...just as soon as I get enough donations to my 501(c)(3) "rear Cayenne caliper donation program", to support this research! :)

Seriously, I am done on this stuff for a while - more projects await. I had a big talk with a friend of mine this afternoon about homebrewing water/methanol injection systems for diesel power and EGT drop. He claims to have found an Ag sprayer pump that puts out the required pressure, and then it's just nozzle selection and a boost pressure sensor for duty as an interlock. It practically designs itself. ;)

I would say 300mm max dia for the rears.... 4.2 AR has 269's...
 

also the rear needs more stopping power to balance out the system but not tooooooo much extra ;-)

No apology required sir. That is impressive. I will be in the brake market shortly. Though I
 

think that a kit might be worth considering so that I don't have to wrap my brain around that many issues at once.

I agree, the factory bias is 2.6 front to rear. I wouldn't want to change this too much
 

without being able to change the proportion of front to rear bais.

ECS has a nice informative article on it.<ul><li><a href="http://www.ecstuning.com/stage/edpd/pagebuild_v2.cgi?html=info-B5S4B6A4-Braking-ECSStage4.html&amp;make=Audi&amp;model=All%20Road& amp;submodel=&amp;engine=2.7T&amp;category=Braking &amp;subcategory=ECS%20Stage%204">here</a></li></ul>