We've been selling the Brackets filters since 1975. Challenger claimed better breathing and more HP for the Cheetah with their new air filter. I was skeptical that the Brackett could be improved upon so I tested them against each other myself.
I took a Cheetah airbox and sealed it up so that we could install each filter and suck air thru them with two shop Vacuums. I connected an airspeed indicator static port to the airbox so that it would read negative pressure. The lower the airspeed the less the pressure on the Carburetor side of the filter. We removed and installed the filters several times to check for consistent readings. The results were Challenger 39 MPH, Brackett 53 MPH. Challenger won.
I don't know what that translates to in MAP, probably a very small fraction of 1" Mercury. A standard MAP gage showed no difference. We used a airspeed indicator because that's the only instrument I had that was sensenstive enough to indicate a change.
I wanted to see if there claim of less resistance was legitimate, it apparently is.