Congratulations! Great color!

2002 4.6 does not have Mark 4 navigation. I found one on eBay offered by a 5 star seller with 98% satisfaction. Easiest way to tell is go to map on nav screen and if perspective is there it is Mark 4.

A plug and play speakers, amp and subwoofer is offered by BSW.

Easy way to upgrade features to have USB, Sirius, Aux and bluetooth is to add add a Dice media bridge that works with existing controls and display info on Nav screen.

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X5 4.6 2002 Black Sap, Black interior. 2013 X5M Melbourne Red, Bamboo interior
Dallas