I'm wiring in an ADE kill switch now. I'm running the wiring and relay to make it look as stock as possible, and hiding the relay in the dash. I have the magnetic reed, the valet and an additional kill switch all wired up so far... I think I hid the additional kill switch so well, I'll forget about it.
And popeye is correct. C103 is the connector in the middle of the firewall, above the engine, closer to the driver's side.... pink with white. Unravel the tape, wire in a switch and rewrap the tape to look like factory.
I read on an Audi forum about someone who went the distance and their kill switch defeat involved 4 other systems to deactivate (A/C, lights, mirror switch and the lit cup holder)... I've thought of that...but having to do that every time seems like a huge pain. I'm keeping my magnet near the switch so I don't have to move it, but I can hide the magnet to activate.
2006 I6 6-Speed X, 33" Goodyear Duratrac, 8.8.