[AudiA4B6US]

Hard to say without knowing what car you have...

 

[AudiA4B6US]

Should be pretty easy plug and play. Since you already have a GPS antenna, you only need the adapters (1x power etc, 1x HF/ZF and 1x GPS) and access to a VAG-COM (or a nice dealer). You will also need to bridge the CAN-BUS signal at your TMC (virtually removing the TMC) and the US navigation DVD.

Check the cables/adapter section here for sources for the adapters. Also check out the RNS-E install pictures. Your's will be almost the same except that you don't need to look for a speed signal behind the instrument cluster.

If you get the US unit from the dealer you are all set. If you get the EU unit you will need to modify the map DVD (search this forum to see how).

Good luck...

 

[AudiA4B6US]

Reading your message a second time I saw that I was thinking you had the CD Nav+ system. But since you are in the US and said it's the stock system, you must have the CD based navigation system (without +) where the actual navigation device is in your trunk. Not a big issue, you just have to get a new GPS antenna (unless you want to router a cable from the back to the front) and disconnect the old BNS (which is the small navigation system).

 

[AudiA4B6US]

From what I'v read, you remove the TMC and bridge the CAN-BUS wires to get the Audi CAN-BUS to the navigation unit. Your Adapter harness would need to have the CAN low and CAN high pins in the right plug (you should definitely talk to whoever makes your adapter harness how exactly this works). The old GPS antenna works with the RNS-E if you get an SMB to Fakra adapter.