Shreddr,
The RPM in the equation is an average of some sort. I will have to look up the formula but it is not linear RPM, so an engine that revs higher gets more RPM credit. I will try to find the formula.
[edit] scratch that, if I understand what I just read correctly (not likely) it is because that torque level is obtained at a higher RPM.
I copied the below from here.
http://www.bristoldyno.com/info/whatis.htm
"There are a few common misconceptions concerning horsepower, torque, and the role they play in your engine and in your vehicle. For starters, they are not independent factors – the horsepower and torque numbers are mathematically linked with a formula: horsepower = torque X rpm / 5252. Therefore at any given rpm, if one knows the torque, one can calculate the horsepower, and vice-versa. In the automotive world, torque is strength and horsepower is the ability to perform work in a given amount of time. So, regardless of how badly one wants that high torque number, horsepower is what actually moves your car down the street or around the track, and horsepower is what tows trailers.
Of course, this does not mean that torque is meaningless. An engine’s torque curve is its fingerprint. It shows how strong the engine is at every rpm. The horsepower curve is merely a function of that torque curve and the rpm. Therefore, it’s not necessarily the peak torque number that matters, but where in the rpm range that peak is, and over what rpm range one can find a relatively high torque, as that will determine where and what the highest horsepower is and dictate how the vehicle accelerates at a given rpm. All engines are designed to be the strongest at one particular rpm range. Heavy cars and trucks have engines with torque peaks low in the rpm range. This results in relatively high horsepower numbers in that range, giving the engines the ability to accelerate those vehicles without the drivers having to rev them up. The successful racecar engine has a torque peak high in the rpm range, or at least a torque curve that doesn’t fall too sharply at the high rpm range where the engine is typically operated. This allows for the horsepower to be at a very high level in this high rpm range. The typical street car is usually somewhere in the middle.
To summarize – a good analogy is a person on a bicycle. Someone with high torque at low rpm would be the weightlifter mentioned earlier. Someone with relatively high horsepower would be Lance Armstrong. The weightlifter may be able to tow a heavy load slowly, but Lance can maintain a decent torque at a high rpm. Guess who wins a race?"