I'm in the middle of doing this at the moment and I expect finishing this project next week, if I'm lucky.
I own a 2019 A3 35TFSI Sportback S-line and I knew that I would convert the rear end to the S3 look even before my car arrived. It was easy to source the S3 look diffuser - some sellers sell them. I chose one from X-uk
here as I used their products before and was satisfied with the quality. The finish was good, as I expected, though I didn't try to fit it yet.
The worse part is a quad exhaust. In the beginning, I was going to source an oem S3 one from a breaker yard. But I learned later that it didn't fit an A3. The A3 has a deeper trunk and there is not enough place for the thick S3 muffler underneath it. Most aftermarket exhausts are too expensive. Finally, I found an inexpensive Polish sports exhaust made by Ulter Sport. The sound was close to what I needed (not too loud, just deeper than stock). They don't make exhausts for the FL A3 Sportback but their PFL version should fit your TDI. I chose a
Saloon version made for a 1.8TFSI because the sales manager said me that it was less restricted than the 1.4 version (more open).I got it for £247.75 shipped to Denmark, received it yesterday.
I don't expect the saloon version to fit my SB, but my auto mechanic said he needed the back box with the inlet and the outlets in the right ends and he would be able to modify and fit it without any issues. Also, I chose the saloon version because it had the S3 look 95x65mm oval tail pipe tips. I changed my mind on the tips though and purchased a
90mm quad tip set on ebay, made in the UK.
Now I need:
1. paint the diffuser black as I have a BE car
2. paint the tips black
3. get it all fitted
Wish me luck.
Harry, is there a muffler under your TDI? I owned a 8PA 1.6 TDI before and there was no muffler at all, just a straight pipe.