The older cars were a bit easier to convert to a manual. You needed someone that was good with software to make it run. So you didn’t have to hack up the dash or install aftermarket dash components or loose a ton of function.
Enter JHM as they were THE FIRST to build manual conversions for the A6 4.2 then made it over into other cars. Most of the conversions are O1E conversions. But the 01E is a pile of shit transmission that has terrible gear ratios and is now so old Audi isn’t making parts for it anymore. JHM makes a speed box for some of the other cars that allows running a better newer transmission. As many of the newer manuals use an electronic speed input. But even with all of this. The conversion would be a healthy chunk of money unless you were willing to compromise.
The ZF6hp Automatic transmission in the S6 is shared in several other cars from Ford Aus to BMW to others. According to some of the Ford guys who hotrod the transmissions pretty good. There is little to no com delay off the paddle. The delay is mechanical or mostly mechanical from what most of the other guys in other platforms have said.
having said all that. Shoot JHM tune and tech guys an email. They are usually pretty good about trying to see if you have the latest update and a lot of the time are willing to try and accommodate if they can. The only thing I will say is that I know for sure in some S6 transmissions if JHM speeds things up too far you get a code for processor speed error unable to keep up or something like that.