Anybody know the fuel Consumption (VOLUME) specs for this pump. (on my '01 HO 5.9) Cummins told me the 'correct' PSI for the pump is 17-19. BUT, as I set my fuel pump to a higher psi, doesnt the VOLUME go DOWN?? SO, I guess my question is whats MORE important a good VOLUME? or PRESSURE??? OR get it somewhere...