20k$. I add the mats (320$), tune (900$ish), mudgards, start button and few bits and pieces. BUT (and it is a big butt), it has 202k km. Not warranty... I typically drive 10k km per years, as I uses my bicycle April-November to commute to work; so the high mileage didn't bother me. Most importantly, the car is absolutely flawless. No stonechips on hood or bumpers, no wear on the leather, ....
I read (across) the thread where you debate about material properties and turbo map/lag; no debate there. 97.26% sure you have some kind of mechanical engineering background.
I know I would need a new turbo + downpipe (+ delete all emission stuff) and tune to increase the power even more, not sure about DSG flash (do they even exist for Touareg?) or other hardware required. This will eventually leads to engine refresh as well I guess.