Curious, what is the compelling reason that you want a BM53 with so much effort when there're BM53 looking modern head units like the Avin4 with all the latest tech+? Can't tell apart the Avin4 from a BM53 head unit.

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'05 E53 X5 4.4i, '97 E39 528, '07 E92 335i, '16 F86 X6M.