That looks like a shitload of trouble to add the stock navi. I was debating to do it when i saw how good the 06+ system looked but when i saw the required work it kinda freaked me out.
From your experience, would you say its easier to add the oem navi if the stock bose headunit is retained? I saw a few unused plugs in my own touring and I was hoping some of the wiring was already there. What exactly is missing to add nav? I imagine the center console and rear panes have to be removed to add the the DVD player.
Let me know when you get a chance, my main issue was creating the harnesses, i dont mind taking apart the whole car, ive removed dashboards etc for navi on my previous cars and to add auto climate. But everything was plug and play, i would add new harnesses with matching plugs or swap out entire body harnesses with the entire car pretty much apart and a million screws labelled aside.
Do you think it would be possible to do the same thing for the Z if i found an 06+ with navi? Im kind of thinking of ditching my avid d3

I just like the stock screen look of the navi. let me know if you would be interested in selling me some harnesses
Congrats on the install.
Sorry for the (inexcusable) delay - I'll do my best to answer your questions:
From your experience, would you say its easier to add the oem navi if the stock bose headunit is retained? I saw a few unused plugs in my own touring and I was hoping some of the wiring was already there. What exactly is missing to add nav? I imagine the center console and rear panes have to be removed to add the the DVD player.
What was missing to prevent "plug-and-play" was the dash harness and chassis sub-harness that supports the navi system. Since my car is technically an "enthusiast" trim I did not have those harnesses in the car. I am not sure what trim you have; there is a CHANCE you have a trim level that is outfitted with a navi dash harness. The other harness required is called "Body Harness #3" if I recall. It is the one that runs to the back nav DVD unit. Again, it is useless unless you have the navi capable dash harness in the car.
The stock headunit is NOT required as the navi DVD cpu produces high-level outputs for the speakers (meaning you can drive a speaker directly using the navi cpu). This is what I initially did, but then later rewired the audio output to the high-level inputs of my amp. Only drawback is that I need the head unit on or no navi audio, but when am I not listening to music?
I initially drove two speakers with no issues, and the volume control was not maxxed out. It was just personal preference to run it into the amp. The stock headunit has the plug for the navi inputs (it is the topmost brown plug). If I stil had the stock headunit and the correct connector, yes I could wire it "like stock". Honestly, driving a speaker or two directly off the navi cpu is easier.
That looks like a shitload of trouble to add the stock navi. I was debating to do it when i saw how good the 06+ system looked but when i saw the required work it kinda freaked me out.
Yes it is a lot of work, all the panels had to come out, including the cluster, and other dash panels to get the gps antenna in the stock location. The whole system pulls power from the correct fuse locations and all components are in the stock locations - the only real "custom" aspect is the control panel fitting, and the wiring itself.
I could - theoretically - make a harness but to be honest, I'd rather draft a "how to" wiring guide and provide that. I saved all the point-to-point wiring connections in a spreadsheet. That was definitely the major legwork - I had to make sure all the pin connections lined up for each plug since, obviously, they are not labelled from the factory

You will also need minor experience making connectors, I used a small variety of AMP polymer connectors to make the control panel and display removable. This is not an easy job but do-able if you have the time a patience. Just depends on how bad you want it really.
And to add a final thought - the 06+ system has minor wiring differences so you would not follow the exact wiring as me (03-05). I have YET to find an 06+ system for sale. I looked high and low before committing on the 03+ system, I really really looked.