ok so if anyone is interested I got totally overwhelmed by the choice of spring with different colour codes etc. I tried searching on eBay for S4 springs and intended to grab the colour codes off the pics but got some conflicting hits.
you need to check the options sticker in the boot or wherever and cross check to the parts base number.
http://www.partsbase.org/audi/audi-...100-suspension-anti-roll-bar-shock-absorbers/
in my case it was 1BD and 0YM
1BD = Suspension/shock absorption for special sports design
0YM = Weight range 12 installation control only, no requirement forecast
So I used parts base and found 2 that matched:
8E0511115DP coil spring; 1 paint mark; 3 paint marks; blue; green; DTM; PR-1BE,1BV,; 1BD+0YM; PR-1BE,1BV,; 1BD+0YM
8E0511115FP coil spring; 1 paint mark; 1 paint mark; grey; yellow; DTM; PR-1BE,1BV,; 1BD+0YM; PR-1BE,1BV,; 1BD+0YM
From some googling the second one is the RS4 and the first is the S4. So ordered those from TPS. 70+vat each but I don't want to lower and Im happy they should sit like OEM.