Just a quick update as a word of caution.
The rear upgrade is perfect for my front brake set-up to REGAIN the balance between the front and back. The front was slightly overbraked with the TAROX upgrade and the S3 upgrade simply redresses the balance at a higher level than before. Upgrading the rear only (in my opinion) isn't necessary and the front needs to be significantly upgraded before the rear needs attention 
....Aha! Not just in your opinion but, in different words, this is what AP were telling me when they said I didn't need to change my oem rear brakes with their AP 4-pots on the front.
Lots of opinions here, my
findings are that with the full S3 Set up, mine is just right. Just my findings, and this has been mentioned to me when my car was worked on recently by a very reputable organisation, in fact they were very impressed by the feel, initial bite, and effectiveness. Now I am
not saying that they will cope with lap after lap of the ring, but what brakes can, apart from a full set of bespoke track (not road) brakes.
The full S3/R32 is a very cost effective and well developed OEM road set up, which is developed by the factory for use on a car of similar weight and chassis (Audi S3 or seat Cupra anyone......). they may not look as sexy as AP's etc, but IMHO bang per buck, road set up they are great.
The full S3 set up offers a far more cost effective braking system, and in most circumstances, i dfeel would be adequate for use on the road, with the odd foray on the track. You will spend sub £500 for a full set if you shop wisely, rather than £1000's on bespoke road brakes.
