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Hello and welcome to Justanswer.com my name isXXXXX'm a Certified Car Expert Mechanic.I'm going to try to help you find the help you need DRC system is relatively simple system, but requires a lot of special tools to work on it correct and without braking anything only difference between changing the springs or service on an RS6 verses the regular A6 is that first you must draw a vacuum on the DRC system Then you can disconnect the lines to the shocks and replace and service parts To install you must again draw a vacum on the system, then use the vacuum to draw new fluid into the system. Finally you must pressurize the system to 22 bar and then bleed the pressure back to 19 bar which is the operating pressure. Failure to do this properly or to put the vehicles weight on the suspension without it properly filled will damage the central valves in the system and they would then have to be replaced and that is very expensive also tool number to work on the DRC system is VAS 6544, it costs roughly 7000 euros so far I know , so my suggestion is to take local Audi dealership (since they have the tool) and have them install .
here is tool info with pictures