I think the "Mopar filter study" done a few years ago was very informative and contained lots of good filter info. The guy is not a filter scientist, but lots of facts and common sense made for a very good study and results.
From what I can find out, the K&N is very similar to the Mobil One filter, both made by the same company. These are premium filters with stronger cases, synthetic media, not paper and a good sealing gasket.
For cruising around town with frequent filter changes, usually not a problem. For strip use with high RPM and oil pressures, a good filter is a MUST. Had a couple name brands blow out and balloon in the driveway on a stage motor GN.
Cut a few filters open and check what you have inside. Not just the trash if any, but the filter media. Have seen AC Delco and other entry level filters with collapsed cartridges. Will do no filtering like that.
Personally, I prefer to spend the extra $5-6 for a premium filter to help protect my motor, as well as for others.
