I did not use a single screw. The unit just sits inside the "hole" for the time being, but it didn't move at all, so I plan to just let it sit as is. I'm waiting for an extended cable to come in for my back up camera set up.

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2002 X5 4.4
2007 335i - catless DP, Cp-e CP, CAI, MHD tuned ~17psi, AG m310 19's.