I heard the mazda suggestion (use mazda parts from mazda speed to improve your Ford Fusion), but it really didn't seem specific. I want to tune my new fully loaded SEL for as much performance as safely possible (or as I tell my wife, drasticaly improve gas milage and overall safety). Looking at the manual, I saw that the mastercraft filter part number was FA-1771. I'm going to check the specs and see if I can find a K&N replacement as a first step, but I've got a couple extra bucks to spend and I want to get after it. I'm talkin' cold air kit, turbo-charger, super-charger, exhaust upgrade, headers, chips tuners, YOU NAME IT! I saved so much money buying the car at just 4% over manufacturing cost that I have so coin to burn. Might as well turn this family car into something I like too! I'm 26 and this car is appealing to me. I figure that there are proly a lotta guys in my same situation: buying power, need for family vehicle, desire for sports car, interest in tuning and modification, etc. Seems like there is a market to exploit... Anyone have any leads or suggestions?