All test results were done at 10”
To convert to 25” multiply (result shown) by 1.580

Required Air CFM based on cubic inch and desired RPM.
(RPM x C.I. per cylinder) / 1925 = 148.05 at 10”
Example: (6000 x 47.5 = 285000) / 1925 = 148.05 per cylinder

--------Stock Harley-Davidson® air filter flows 130 CFM at 10”

--------Harley-Davidson® Stage 1 Screaming Eagle™ flows 160 CFM at 10”

Test results provided by Horsepower Inc. (814) 835-4941