I think the point has been made that they obviously forgot about 4 wheel drive cars with their compatibility with an 064 turbo frame, prawn fitted one a few years ago (after going through his thread ) but has an FWD A3 - whereas you have an S3 so a downpipe on the wrong side of the turbo.
I think you have moved on from the TTE now in any case, I am surprised that Si from TTE has not said anything on this thread?
If no one tags me I will miss posts sorry.
The K04-064 type TTE hybrids we offer have never been advertised as plug&play just that the turbo bolts on with supplied hardware (no spacer needed). Sorry if anyone would think it is plug & play. I will update the listings, saying much work involved, later when have time.
Much work is involved to go this route in any case FWD or AWD but many been sold over the years so guys do feel worth the effort. TTE hybrids offer very good response and power and are super reliable.
I just asked the question on our TTE owners group on facebook and a customer came forward with A3 1.8T with AWD and TTE390(K04-064 hybrid) fitted no issue with transfer box.