And please don't write in text speak, its highly annoying (from one Scot to another )
Cud u tell me the size of discs I need front & rear for A4 2.0 tdi 170 avant?
you can fit S4 breaks
as long as you have all the parts
If you look on the chassis/build sticker you can determine the size of discs from that - 1LZ (288x22mm), 1LB/1LE (288x25mm), 1LT/1LF (312x25mm), or 1LA (320x30mm).
But to be absolutely sure your best off measuring.
Oh, regarding the RS4 brakes, have you priced up the discs alone?? - i hope your sitting down.