Should there be something between gas tank and trunk floor? On the straps?

There is the mat above the tank and the floor, but I used a teflon tape the same width as my straps between the strap and the tank. It's not the white pipe tape, but a fiber type, very strong and wear resistant. It is a product used on helicopters between removable panels to keep wear down as parts move. SAINT-GOBAIN, PERFORANCE PLASTICS.