FWIW...Patrick James at Pro Systems told me if the car does NOT run faster w/ the air cleaner removed, then the mixture is off. It SHOULD be faster w/ no air cleaner.

Unless you're having some sort of air turbulence issue at speed which is very possible. An air cleaner can help w/ that.

I don't run one at the track b/c I can only fit a small diameter air cleaner w/ a short filter on mine...just use it on the street. It's like 9"x2" or something like that.