I used to work for a company that built about 2/3 of the structural parts for Gulfstream's GIV and GV models. Gulfstream introduced their GV specifically to counter the Global Express. It seems that Bombardier has beaten them to the punch again, but I'm sure Gulfstream will up the ante with a "Rolls Royce" type jet like always. They were partnering with Boeing on a supersonic business jet years ago so I know they can do it. Only question is, is there a market for it?