40-50 more passenger seats? I would have thought that their aircraft would currently be very close, if not at the maximum allowable by Boeing and the FAA; the maximum being the amount of people able to exit in an emergency in a given time. That's the original certification and I would find it unlikely that they could get an STC for something like that, unless of course they added more exits to the existing aircraft.
Didn't O'Leary make this joke last year to get free marketing?