Moparmal, don't forget we race cars with motors, not motors on dynos The reason I'm pointing this out is I saw 8 HP loss on two different motors on two different engines dynos at two different altitudes testing the K&N Extreme filter lids and eventually ended doing a at the track test back to back to back, A,B,A, in less than twenty minutes between each run and saw a .020 to .030 ET reduction(quicker) and .3 MPH increase on a 3x14 filter using the lid This was on a 440 powered Duster with a sixpak type scoop molded on it, the air cleaner lid was close to the top of the scoop, less than a fingers width at the rear It was not sealed to the scoop either some of this hot rodding and race stuff doesn't always make since, HUH Test, test and test some more to learn whar does work