[Drothgeb]

I ran them for years with no “stud” issues. The biggest problem I had, was the nuts were too big to fit between the valve covers. Even with countersinking the washers into the head, the edge of the nuts would eventually cut the valve cover gaskets and cause a leak. Finally switched to 625s.

As far as breaking them. When I bought mine, they sent me a couple of extras. I put them in an old block and head, and pulled them to 190lb+ without a failure. Not sure how long they would last like that, but I was still impressed. I think the heat treating with the Extremes was pretty variable. If you got a good set, they were good. If not, then???