Grey to Green: +22 GP
Green to Blue: +23 GP
Blue to Purple: +22 GP
Purple to Gold: +24 GP
Gold to 6E: +45 GP
So your all-gold mods are granting you +300 GP over him. However; his extra G12 piece is granting him approximately +209. Hence the +91 difference in your TFP GP's. Obviously gets inflated when you see the green "+#GP" when you assign mods or gear on a crew member because it reflects their increased GP along with their increased crew power contribution and ship power increase.