Flames from the exhaust has been around for a long time. I'm not sure of the origins but I've seen old photos of flaming tailpipes from the 40s. Today, the rat rod crowd is doing it and using propane piped into the exhaust with igniters to fire it off. There's a guy here in town with a rat rod 31 coupe, Olds engine with zoomies that point straight up. He carries a propane bottle like used on a gas grill. When he fires it off the flames will go up about twenty feet. Don't have a photo of the flames but this is the car.
Tom