Well if it's intended purpose is for off road use only and you wreck in the street then I think they're probably covered.
If that failure directly causes an accident on the street that lands the driver in the hospital or worse, they can't hide behind their little "Off road use only" clause.
Even with that clause, the drag strip counts as "off road" use and that is where this part would be under the most stress.
I wouldn't want that sort of liability on my hands, that's the sort of thing that keeps you up at night.