Useful to know about the TTV. Saw some pics of their lightweight S4 version on FB today. Its a pretty nice piece of work, although a 6Kg flywheel might not suit the character of an S8!
Don't forget the ECU - £600.
If you are intent on doing this then sort your clutch pedal first. After that everything else is gravy
Tricky to source, yes, but at least it all exists!
Oh, don't forget there is no shifter surround for RHD manual either. Not exactly a big deal to adapt a shifter boot to fit the tiptronic surround, but it still needs doing