Well, it looks like they calculated the ramp fairly well, and maybe even the thrust. What they apparently failed to calculate was that a crappy mid-'70s Ford product would fly to pieces at 300 mph.
That was awesome. Reminds me of Hooper, except with disintergration. But I digress: The barrel roll from Man With the Golden Gun beats that regardless.
He's lucky he landed in the water. Imagine slamming into the ground at crazy speeds like that? I guess that's what you get for living your life trying to please others.