The pax limit on Gulfstream aircraft is controlled by the size of the exits. The Exits to comply with FAR 25.807 for 19 pax require two type III or larger exits, one in each side of the fuselage. For 20 to 40 pax you need two type II or larger exits. The G650 has four type IV exits, two on either side plus the entry door. This arrangement has been submitted to and accepted by the FAA as an equivalent safety finding to theType III exit requirement, therefore ,a limit of 19 pax.