The electrical connection you have on the SLIDE from the M273 fits without any modification to pins but the Audi RS6 has a different plug and another assignment (and other pins). A wiring harness adapter is recommended. VW p/n# 1J0 973 713 - It can be found here as connector kit 17025: 

 

You will need a new housing on the compressor with an 80 mm. out-let. In EPC this is called a PIPE LINE and the MB part number is A113 140 09 12. The price is about 240€. Also an adapter plate between the new 80 mm. PIPE LINE and the 82 mm. SLIDE; as well as for the 82 mm. throttle body from Audi RS6 is necessary. This adapter plate can optional be welded onto the PIPE LINE and machined to fit and if you go for that, then you can use your original PIPE LINE.

 

Following original Mercedes Benz parts will be needed:

 

- GASKET; ELECTRONIC GAS ACTUATOR TO INTAKE MANIFOLD: A273 141 06 80

- GASKET; INTAKE FITTING ON COMPRESSOR: A113 141 07 80

- GASKET; INTAKE HOUSE: A113 141 15 80

- HOUSING; DISTRIBUTOR LEFT AND RIGHT: A113 094 02 03

- CLAMP; DISTRIBUTOR TO HOSE; A008 997 44 90 – CHECK THIS

- GASKET; ELECTRONIC GAS ACTUATOR TO INTAKE MANIFOLD: A112 141 13 80 (not needed if adaptor plate is being welded)

 

Ten o-rings come in the package, you need only two for each application.  Remove the plastic retainer and rubber seal from the y-pipe, replace with two new quad style o-rings, and assemble.

Note: This is for the MB 82mm throttle house being used in conjunction with the 80mm y-pipe. I pulled the rubber gasket and plastic ring out of the inlet connection. It measures XXXX with these removed. Mcmaster.com has o-rings with an inside measurement XXX and outside of XXX which should work.

*This I am still working on*

 

Since you will have to remove the compressor from the engine to make this modification you will need new gaskets for this too:

 

- GASKET; CHARGE AIR LINE/COMPRESSOR ON CYLINDER HEAD: A113 141 09 80

- GASKET; LEFT; A113 098 01 80

- GASKET; RIGHT; A113 098 00 80