I'm trying to customize a bluetooth car kit for my aftermarket stereo. Knowing that most E46 come with prewire for the OEM BMW phone kit, I want to be able to take advantage of that. Does anyone know where the microphone and its wiring located at? Any connections that go to the back of the OEM stereo? I've heard that the microphone goes on top near the center console lights location, but I don't want to remove the head liner in order to gain access to it.