You say you have it connected on top of the filter? I would connect to the schrader valve on the VP!! Thats the reading that is most important and if you are reading 11-12 pre filter you may need to upgrade that LP with the mods you have!!
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01..4x4..NV45..
Adr..BHAF..Boost Elbow.5" TBE.Big Lines & Draw Straw.
Holly Blue.Dipricols.BD short/shifter..
scanguageII ITW:Valair DD, 64/71, DDP's, Pulse, AD 150, HTT Mani.The Best= Holland Court & Coaltrain.