well my current oem sline one seems to be blowing and tailpipes are black. was gonna just get it replaced but found ad for s3 one only done 4000miles when taken off! i dont want a miltek as im not into loud exhausts but like the sound of the oem (not too loud nor quiet).
The S3 exhaust will fit a 2.0TFSI Quattro, i have looked into this before.
The bore size from the CAT is the same, the only difference is that the rear exhaust hanger on the S3 is different however the fixing points of the hanger to the chassis is the same. So you will need an S3 rear hanger.