I have always wondered about putting on the freer(sp) flowing intakes. Does the computer automatically squirt more fuel due to more air, using the air flow sensor, or as in the case of my NON-computerized harley, lean out the mixture. Now with the more HP, the engine doesnt have to work as hard to get the car in motion. I'm guessing that is the case of the mpg increase(If the driver can not use the lead foot as much, I know I couldnt haha).