[f5fstop]

Mapping software is not that large. I have Garmin Street Maps, which contains all the same information as the Pioneer Nav, and it is contained on two CD-ROMs, and is not compressed. So, that's about 1.5 gig.
(My Garmin total USA Topographical set, is only on three discs.)
Gracenote is a pretty large data base, the update was about 400 meg, and I'm not sure if that was an update, or a total new file.
Operating system takes quite a bit I'm sure, but here must be about 10 gig non used. Just my thoughts.

I had heard that on later systems the Z1 did not work. Give 'em some time and someone will find a way. I guess I'm lucky, the Z1 works great for me.

If yours was manufactured in July, you probably don't need the Gracenote update with is dated in June.

The times I have tested onstar for the alterator whine, and the one time I actually used it to place a quick call, did not produce any snaps or pop. Even with Bluetooth, there is no snapping or popping, and the owner's manual warns you that it can happen. Only problem so far with Bluetooth is I get complaints from people saying they receive an echo. Something that is common with Bluetooth setups.