[Purchasing advice] Audi S6 Plus C4

Hello dear forum community,

hungry for more power and once again a bigger car let me come across the S6 Plus around 1996.
The fixed thing is: manual transmission, climate, leather with Alcantara, BOSE (then I don't have to retrofit wildly)...

I would be interested in the following things:

- Spare parts supply
- Typical defects
- registration of tuning parts (since yes Quattro gmbh - e.g. Of a kind used in the manufacture of motor vehicles
- Things you would not forgo in the car (some gimmicks you like)
- Euro 1 or already Euro 2?
- Adjusted at 250, is it true that you can easily unlock it with the tester?
- tank size
- Loss of value

You may also refer me to other threads.

At first I wanted an RS2, but after many conversations and various computing and rational I would like to now a S6 Plus.

Best regards
Sören from Norway