Hi all - I'm new here and eager to get my system working. Just bought an AVIC-Z2 and was installing it today. After a bit of a surprising discovery and some mad Google searching, I sent this letter off to pioneer electronics. am i crazy? 
Hi--
I recently obtained an AVIC-Z2 for use in my 2007 VW Jetta. Now, at the time of install, I note that the AM/FM diversity antenna integrated into my car has two antenna output cables. The OEM radio has two antenna inputs and does the signal processing internally to achieve the best reception.
Since the Pioneer unit doesn't have diversity reception, I have to drop one of the antenna leads and sacrifice the benefit of the diversity antenna.
It would be great if Pioneer made a small module that could do diversity reception on its own. It could then output a single antenna lead, with the rectified signal for input into a Pioneer head unit. The module could use an IP-BUS connection in order to know the desired frequency as requested by the radio user; diversity reception "decoding" apparently relies on using the currently tuned frequency.
I know that many people think terrestrial radio is on its way out but I strongly disagree; the overzealous data compression of satellite radio and its cost make it an unattractive option. Since Pioneer has had such a great history with the SuperTuner series, I would think this idea would have appeal to the Pioneer product managers.
Thanks for your time.