After months of struggle, Maser finally warranted the radio system in my coupe. Now that I have the car back, I was playing with the buttons and on hitting the NAV button it asks for the NAV cd. My car didn't come with nav, and this is a different error than before. I am wondering if the new head unit came with nav, and how to be sure, or, do all newer units give this error when pressing the nav key? Where do I get the cd?