Does a PowerCAP really bring anything???

Boys and girls, I need your help. Quite simple question: Does a PowerCap really bring an audible improvement of the sound at higher performances??? And if so, how can you put it in numbers (and formulas)? (Instruction for this thread: In another forum you don’t believe that a PowerCap really helps what. And I just don’t want to leave it with this misbelieving.) Ask for competent answers.