In all but the hottest weather you will notice a moderate increase in power. In hot weather you will have a power decrease due to pulling in hot air from under the hood unless you figure out how to install some kind of heat shield or it is truly some sort of cold air intake that draws the air from somewhere besides under the hood.
Most of the difference you will notice, however, will be auditory. It will sound a lot better, especially under full throttle. The Duratec really sounds great when it is working and even slight changes in the intake or exhaust really show it off.
