For those wondering about limits - I don't have any hard #'s, but I did manage to shatter a window on our front door while attempting to remove a crank bolt on an Acura in our driveway. After my impact gun failed to do the trick, I put my 5' cheater bar over an old 'Long C' craftsman 1/2" breaker bar and hung on the end of it (I was pushing 250# at the time). Rough math suggests I was putting 1000+ ft lbs to it when it failed. Sounded like a rifle went off and the window shattered. Took me a sec to realize WTF happened. Ended up doing it again with a snap-on breaker bar and finally got it to break loose.