Normal range is 45-55PSI at the upper filter housing. Since the by-pass should be over 55PSI your readings will fluctuate depending on the fuel system performance. I doubt you would ever find a clogged filter causing a drop in fuel PSI. More often the HFCM will loose output and cause lower than suggested PSI readings. There is an updated fuel pressure spring kit from Ford and International that gives an slight increase in normal PSI at the housing. Additionally you can add an AirDog system to help filter out air, water and debris while providing a steady source of fuel to the HFCM. There are more options as well with the ADII so if you have more questions just post up.
