I'm pretty torn, to be honest.

The Mediabridge is less expensive but I'm not too keen on tapping into wires based on the installation videos I've watched. Unless it's the same for the Grom unit.

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E38 740i (9/94, GF61, JPN: M60B40, ZF 5HP30, 3.15:1)
E53 X5 4.4i (5/06, FB53, US: N62B44, ZF GA6HP26Z, 3.46:1)