Against BMWs strict guidance I've driven both e53 and e70 without the stiffening plate. On the e53 it makes a much bigger difference. The drop in torsional stiffness immediately reminded me of driving my '95 Z28 with the top down. Jiggles from every pothole. On the e70 did not really notice the difference it's clearly a lot more subtle. That said, the biggest problem of either not having the plate or not torqued bolts is the main strength of the plate is to keep the car from becoming a parallelogram from a minor corner impact. Basically bumping into a light pole in a parking lot might total the car without the plate in place with stupid high torque on the bolts. There is reason to the nuttyness.

That said m10.9 spec is 67 N·m and that will get you 7500# force. At yield 9000# the problem is when you "snug" them as if the plate is not structural the clamping force drops so far it stops being structural and you may as well leave the plate off. (The majority of the resuse crowd will fall into this group)

67 becomes 50 N·m when oily (which is pretty common on older X5), so it's impossible to get to a proper clamp Force on a reused bolt, it's just something people will decide to do. The diagonal loading forces become astronomical with a minor corner bump it's definitely best to have maximum tension on the bolts. (But as mentioned I've driven with zero tension on the non existent plate). Just be informed.

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2011 E70 • N55 (me)
2012 E70 • N63 (wife)