Let the test results show, I am the father of the air box to spa filter conversion!? Is there a way to post videos on here?! No to many people thought this mod was gonna pass. But after some testing on the factory air box and tuning the spa filter with foam I got it to the exact same flow as the factory box and filter. Mock up for start up test and rev test. And WALLA! Idled perfect for about 10 mins, rev perfect any way I mashed or held the throttle.