Originally Posted by ARCOgraphite
Then you have Ecores with high pleat count - but shallow pleats ( due to the large core dia.) and a resultant low surface area,
My eyeball test looking to the bottom of the filter tells me there is no discernible difference in core diameter. My ruler tells me the STP and Purolator pleats are both 10mm tall. The Wix pleats are 14mm tall. Not convinced the 14mm tall pleats make up more surface area than the considerably more 10mm pleats jammed into STP and Purolator filters. The Boss is also full synthetic and plastic mesh backed so that one is probably not apples to apples.