As above i need a milltek or similar back box for my 1.8t quattro have the cat back in milltek already but a new back box is about £230 and i'm on a budget,
Them Xs power stainless ones go silly cheap sometimes. May be worth taking a punt and then getting a 2 into 1 adapter made to fit it
I have an OEM S4 system on mine from just in front of the mid box back