If the bolt is tightened down against the stop it is not going to back out. For 6/2015 and later cars the torque spec is 1Nm (8.85 in-lb). For 5/2015 and earlier cars, that use different hardware, the torque spec is 5 Nm (44.25 in-lb). An alternate method is to get a short metric (M6) stainless steel bolt, that is slightly longer than the depth of the threads, and a rubber washer. Put the washer on the bolt and run it into the threads until the bolt head tightly clamps the rubber washer to the bracket. I just noticed that my instructions say the maximum limit is 150 lbs, not 165 lbs.