We tested my air pan setup when my current 410 c.i. small block was on the dyno a few months ago . Weather wasn’t optimum for testing and it was’ t an actual sealed to hood test . We made pulls without the setup ( open carb , no air cleaner ) and with my filter / air pan .. the results were : No loss or gain in horsepower or torque with the air pan or without . I am sure there is a gain when in the car especially in cooler air . It is good to know however that my setup isn’t hurting my performance , I like having the air cleaner especially at dusty tracks.