There is an interesting article on David Vizards web site on induction volume 3. In it he states that he could look down the carburetor on a dyno pull and visualy see that the intake valve was glowing a nice red color.

He had thought this might be heating up the air intake charge. So he had the intake valves coated and noticed a slight increase in horsepower. I mentioned this in one of my posts and Stan Weiss reminded me that on a fuel injection system(not all) the fuel is sprayed to the back of the intake valve. So this could cool the intake valve and inturn provide for better atomization. Just a thought.