[Charlie]

I'm not suggesting that a 351 sounds like a 427. All I am saying is that it can't be because of the firing order. And that you can get that pressure pulse in your chest from many engines, not just a 427. A quick visit to the NHRA nationals will convince you of that. There is something else that causes these effects. Actually, xlr8or is probably on the right track, that it is the unique combination of ALL the engine variables like port size, displacement, exhaust system, etc. that produces the sound, but I think it is the horsepower level that produces the shock waves we feel.
So if someone will donate their 427 engine to me for scientific study, I will get to the bottom of this mystery!