I see no problem with mounting upside down. I was at a local hydraulic shop who rebuilt my steering box and pump recently and I was told that the return port on the booster was higher than my reservoir which may be causing some of the pump whine and wheel feedback. So I will be flipping the hydroboost soon and will post some pics! BTW, I had a reman Napa pump ($76) on the car and it was the loudest whining POS I have ever seen, worse than any typical ford pump whine. I had the local shop rebuild my original pump and it is remarkably better and quieter ($45). Next mission is flip the hydroboost (going to look much cleaner with all lines underneath) and buy a better reservoir with seperate -6AN returns.