OK nummers.
Ive owned a modded RS4 and it wouldnt go close to an SS. Ive also owned a stock 260, this would not go close either (its a weight thing, they are a slug when standard). Now chuck a TT kit on the SS and you will see 11s straight away, this can be done for $10k or less. Now I went and modded the bejesus out of the 260 and got it down to a fairly respectable 11.7 down the quarter.
To settle this, get your RS4 to the strip and get a slip. Find someone with a stock SS and do the same. Be a man and stick up the evidence here.