yep its been discussed a bit before, do a search to find details but basically to replace the front bumper you will also need wings and liners as the S3's have flared arches, but they all mount up on the old A3 brackets. The Rear bumper will fit on but again as the rear arches are flared doesn't fit that well where it meets the rear quarters, although i beleive some people heat up the bumper and flex it to fit. Also the exhuast on the S3 exits differently to the A3 so would need new rear box, i think people have had custom rearboxes made by powerflow and similar companies rather then fit the S3 one because it isn't a direct fit.