Impreza01, you hit it right on the head when you said "reported". The SAE formula is the same but some manufacturers will be more aggressive or conservative in their reporting. ie. Ford with the Cobra and Mazda with the Miata (in recent years).
As far as top speed acceleration goes I think that hp/coefficient of drag becomes more important than hp/weight as speed goes up.
I agree that the gearing is a key to a cars ability to accelerate, look at the WRX 4th gear and the Acura CL-S automatic.