there was a chap on TS.net that tried to put the centre console off of a facelift into his pre-facelift S3 but despite the console/double din cage fitting ok, the wiring for the aircon was different despite the electrical plugs being the same. I'm not sure if he finally managed it or not. This would all have to be addressed before you then fit the SATnav and all the associated wiring. While I doubt it would be impossible, it would be a lot of work to do yourself or a fortune to pay somebody else to do. It would help to have the wiring diagrams for both models plus the SATnav system.