Loud Whine

Im pretty "car stupid" but was smart enough to buy a ford :P, its a '88 Full size bronco, 351w, 3" lift, 33" tires, true dual - flowmaster exhaust with hedman headers. My problem is when i fire her up i here a loud whine (its air for sure), and its comming from (or around) my air filter (its a k&n). I have recently cleaned the filter and i cant seem to pinpoint the sound. If anyone has an idea where that loud whine could be comming from please help me out. I have had my truck for a year, its my first, and its my baby, please help.