You'd be very very surprised how quick even a mk5 tdi can be, back when I had my S3 that was revo'd, I'd quite often be shocked at how damn quick those things really could be from a start, of course top end of the mph we'd show the S3 capabilities, but they were damn nippy even against my S3 that wasnt any slouch Leggy, so a mapped tdi wouldnt surprise me whatsoever if it was a challenge to the S3, those new 140's are seriously quick, went in one unmapped & you wouldnt beleive how quick it really could be if driven right, so mapped I can only imagine mate how much nippier it can be also.
Yeah V12 6.0 Q7 may sound the nuts, but take into account weight, this is what was the big issue with the B6/7 S4 V8, I had the B6 S4 avant & S3's used to give me a hard time, cause of the weight overall, was too heavy really to put it down as such, lovely car but preferred my S3 overall.