Any ideas where this might actually be?

Or, how does it affect the Z1 if I don't hook it up? (I dont have a reverse camera installed nor do I plan to).

Reverse Light white + back of fuse box, 9 pin plug, pin 5

I found this a while back however it is incorrect. There is no 9-pin plug that I am aware of. Also, there are 3 white+black wires I found coming out of the fuse box area.

If you're not going to use a backup camera, then there's no real need to hook up the reverse wire.

Alrighty, install completed! Thanks for all the help. Navi works great and looks even better!

Not unless you drive extended distances in reverse, or are on the A-Team.

reverse wire is a blue wire that can be found in the back (drivers side) of the trunk.