At what HP /rpm level are billet main caps and or stud girdle needed?

This answer won't be received well but I don't care.....if your asking yourself these questions then the best answer is to just buy a real block and then it will come with good caps and the girdle won't be needed. Personally I think those band aid type supposed fixes are only endorsed by home engine builder type guys who typically always try whatever is cheapest first and professional builders know better and would tell you the same thing as I just did. "BUY THE BEST CRY ONCE"