I didnt see the show but for propane to act like boost it would have to be injected as a liquid under pressure. Which is what they obviously were using. Vs the other way propane is normally used in forklifts and such consumed as a Vapor

Propane is in liquid form under pressure. Once relesed it expands x%

Propane in Vapor form has never been a good high performance fuel.

But Liquid propane injection, thats something to keep an eye on, mike