adding a secondary fuel filter to my truck (C5500) and I'm going with the same setup as the Nicktane... bought all the parts separately myself (would have bought the Nicktane kit but was afraid of duties, etc as I live in Canada). My question is which side of the filter head is the inlet side? Does the filter work from the inside out or the outside in? Does the fuel come in through the middle of the filter and then get pushed thru and then out? Or does it come in from the outside, and filter towards the middle, and then straight up and out?