I would not remove any filters at any time on anything,thats asking for trouble.Im pretty sure the fluid is filtered on its return side,which would not affect pressure.Im thinking your pump may be getting weak.They really arent that expensive.Check with Mill Supply or Angelos for pump only,not the whole unit.Make sure your motor is turning full RPM also for this would affect pump speed which would affect pressure.I have four E47s Im running ,one of them is slower than the other three but so far its still going strong.Good Luck