There are TWO different PSIs for the AirFusion EVO. 1) the drop-stitch side chambers inflate to about 6 to 8 psi. 2) The thwarts for the bow and stern inflate to about 1.5 to 2 psi. The coaming takes only a pump or two for its inflation - do not overinflate this ring around the cockpit. A standard double-action pump should be capable of these various inflation levels.