To the original question; an oil pump pumps oil through clearances in certain places and creates oil pressure. A high volume pump does not pump a single milliliter more oil with a certain oil pressure than a regular pump. If it pumps more oil, the pressure will raise. What the hi volume oil pump does, is retain oil pressure better with bigger clearances or if problems occure. As long as there is oil in the pan for it to suck. I have always used hi vol pumps, the current engine has the limiter at 7800, makes over 1500 hp and has 7qt of oil in the pan.