I agree that K&N filters do not filter as well. But I have always wondered how much additional wear they could be adding to the engine. Let's take a typical honda 4 cylinder. 250,000 miles is easy to do if it's been taken care of, ie oilchanges, tune ups. Now, what decrease in life are we talking about? to 200k? 240k? etc. At some point, I decided that if I can "only" get 200k out of my B18C1(integra GSR motor) on a cold air intake with K&N, I suppose I am ok with that.