http://www.nicoclub.com/articles.php?id=294580
zer...age=1
The first link is to the AVIC D3 installation write up
The second link is to a good Q and A session regarding aftermarket vs factory nav systems. As you'll see from the many discussions, usually aftermarket systems are superior for a number of reasons, not to mention cheaper!!! Plus aftermarket nav units come with DVD players built in, in addition, you can still retain steering wheel control of everything except bluetooth, but you can purchase aftermarket bluetooth units, XM units, and rear view cameras all for LESS than the factory nav units!
Check the links out, and if you still have questions, just hit us up!!