As far as the '03 Cobra is concerned the AirCharger was released first and had an aluminum velocity bell (Lovingly referred to by many as the "Magical Velocity Donut") vs the plastic one that comes with the current FIPK. The original AirCharger had a shorter filter too if I remember correctly? The other major difference is the FIPK is C.A.R.B. certified where the AirCharger was not. They are both funtionally similar though.