Well guys, I don't mind to get beaten up if there is something to learn in the process: what makes the 'velocity suffer' and where? Assuming constant flow (in CFM, but more accurately the engine sees lbs/min), a larger throttle body decreases the velocity through the TB. Fine. But why is that velocity decrease (and only across the throttle body; the velocity in other areas does not change since the cross sections don't change) create a loss of power?
I hope that none of the critics disagree with the rule: 10 flywheel horsepower for every lb of air (1 lb is 13.16 cubic foot at normal conditions) (the commonly used range is 9.5 to 10.5). More pounds of air through the engine (with the matching fuel to go along) = more power. Or how do you explain the additional power of turbo chargers? They are nothing but air pumps. quod erat demonstrandum.
I am NOT saying that a larger throttle body automatically allows more air through the engine; but if the TB is LIMITING the possible flow, removing the restriction will increase flow (and sufficient fuel available, increase power). Removing ANY restriction in the air path with have the effect (cleaning up your secondaries, UIM, LIM, high flow air filter,etc.). Increasing the air density will have that effect also (colder air, but also lower altitude, barometric pressure)