FWIW, we torque the lugnuts on the drag cars and vintage TransAm cars to 75-80 ft/lbs. Zero problems ever, and the TA cars certainly put that stuff to the test. Not debating new street car lug nut torques, I've heard some pretty big #s like Stumpy says.
I'd take a look at how the studs meet the back face of the wheel and the interface between wheel/drum.
I'm curious about the problem, please report back with an update.

I've ran SB drilled (not unilug) Cragars on my Formula S for about 2 years. I installed long studs all the way around and used a drill press to drill the centers out of the recommended lug nuts for these. After having multiple issues with unilug BB Cragars I won't buy another set of those as I have torqued those to 75 ft/lbs as I did my Formula S SB. The unilugs seem to eventually get/come loose.