Do you mean the head unit?

If so, just stay stock.

There's nothing wrong with it and the navigation is faster than aftermarket units. It doesn't have all the cool features of the new ones, but it is a good unit (the dvd based Mark IV, anyway).

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Kirk
Las Vegas
2016 X5 40e Mineral White/Black Dakota Leather, ZLL, ZCW, ZDA, ZDB, ZPP, multi contour seats, rear side window shades, HK stereo
2011 E90M3, 6-speed manual