A friend had a '65 Satellite with a sealed Hemi style scoop, no air filter and a flat air pan over a 360. Car ran well but occasionally slowed up on a run, then went back to what was expected. He cut a few "vents" in the sealing foam and the car stopped the random slower runs. We figured it had something to do with turbulence. I'm sure a good filter assembly or at least a good baseplate helps minimize any possible turbulence.