I've tested air cleaners, air cleaner bases and K&N filter tops on an engine dyno and at the track, the K&N filter lids on the engine on the dyno lost 3 to 8 HP (CRS exactly: whiney:) At the track with Hemi hood scoop on one of my old race Dusters the car pick up.3 MPH running it versus a raise center chrome or steel lid: confused:
Every car that I have raced (with and without a scoop) without an air cleaner ran slower and less MPH than with the base only on the carbs. and or with a good air cleaner element
I use drop base air cleaners as large as possible to help run as quick and as fast as possible which insures the motor lives longer and doesn't screw up the ring seal due to dirt and debris getting suck into the motor any time it is running