LOL I'm glad I decided to drop in on this thread! You joker!
We all know that lots have people have fitted S3 brakes to their standard A3's, I'm sorry to announce, but loving the pics anyway!
My S3 caliper bolted on fine, and my disc fitted on the hub fine, but the two wouldn't fit together. I could get one caliper bolt in, but swinging it downwards to fit the second bolt, it was coming into contact with the disc, preventing me from fitting the second caliper bolt. The next time I have the time and space to get the car up, wheel off and caliper/disc off, I will try again. I didn't have the time to hang around and investigate fully last time, as I was using a bodyshop's workshop. I have said before that I'm willing to accept that I did something wrong - it was a few months ago after all, and I can't remember the details. I just remember that the disc was hitting the inside of my caliper, stopping me from getting that second bolt in!