K&N filters

As far as I'm concerned K&N amongst all the other similar intakes are less restrictive than stock. I do think they allow the engine to breath & perform better but other than that, I have never noticed any increase in mpg. As far as clogging the mass air, that will occur if too much oil is used when servicing the filter. I do have to say, having added my K&N along with "Cat Back" exhaust the truck performs much better when towing. Those two enhancements work well together. IMHO