Don't get me wrong, there is a place for 'performance' filters - race engines that get stripped down every 5mins and new bits thrown at them, and they are good on normally aspirated stuff where getting the air in is the most important thing.
Not so good on motors that need a long service life or have efficient turbos/chargers. Have seen a good few well etched impellors from all the crap that gets through a performance filter that's been allowed to load up.
Jim


