Hi guys, I'm hoping someone can help me with some (hopefully) simple questions about replacing the head unit in my 2006 A3. I have the 3.2 VR6 which means it's also the S-line package. The current unit is badged "Symphony" and has a built in 6-cd changer and a tape deck. The speakers are marked with "Bose premium sound" or something to that effect. So here are my basic questions: 1) Can I replace this unit with any standard double-DIN receiver assuming I get the replacement facia piece from somewhere? I was pretty sure I could, but it wasn't reassuring when things like the Crutchfield website tell me I can't use double-DIN stuff so I just wanted to confirm with someone. 2) Since I have the Bose branded speakers, does that require a different wiring harness than would otherwise be used? 3) I understand that I can make the controls on the MFSW talk to a third-party head unit as long as I purchase a couple different adapters and can fit them in behind the unit. Is there any hope of doing something similar to get the audio/nav functions of the DIS working with a third-party unit or is that just going to be blank? (The top portion of the DIS I mean.) 4) Is it true that there is a GPS antenna built into the factory "shark-fin" antenna box on the top of the car even if the car didn't have factory nav? If so is it possible to hook that up to a third-party GPS or is it better to just wire a new antenna under the dash? I've done a lot of searching on forums and such and while I've found some promising information, usually it's about a different car model than the A3 and sometimes different sources conflict. Thanks for any insight you can provide.