Did you have to remount your stock deck in the trunk for the nav to work right? Mine goes in for install in a few days, and keeping the nav working correctly is the biggest issues. My installer says it shouldnt be a problem, but I am trying to gather as much info as i can so its not a big issue.
If I'm reading the diagrams right, you need no stock deck for the nav.
You would only need it for the stock amp to work.
If you're going to get an aftermarket headunit, just get a separate speaker and hide it away.
That would be ideal. I wont be using the stock amp, and want to save room by not having to go through the stock deck. I have all the wiring diagrams, and a bunch of info from threads that i printed out, so i will have to look it all over with the installer to do it without the stock h/u.