Ok, here's the response I got from them-
>Mike,
>If it makes you feel better, I've been using them on our twin turbo test
>car - the Z28tt

I've snapped an axle, torn a driveshaft, bent 2 other
>driveshafts, snapped a torque arm and bent another torque arm (all within >2
>seasons!) and the adapters have always been fine. We have never had a >broken
>set, and customers have been running low 1.5 60' times.
>Andris/SPD
>Little M engine buildup in progress!
So I guess as long as they're torqued down good there's nothin to worry about.