Your numbers look good, so i guess K&N is doing a great job, for you. BUT...
50% more flow? That sounds like some crap off the K&N website. I'll need to see the tests...
Foam does deteriorate over time. But then so does cotton gauze. And i'd bet my bottom dollar the filtering efficiency of 2 stage foam trounces the gauze after 3 cleanings (the cotton woven fibers being unevenly laid out after a spirited wash.)
I have seen some testimony of burnt foam filters, but most were on carburated triumph cars with a wicked backfire and an over active pcv system (the filter being bathed in engine oil). I have yet to see a backfire on my car, so I'm not too concerned...
BTW, I would see fleet operators and rental car agencies using oil analysis to minimize maintenance costs. And I think we'll agree most of these vehicles see a spirited life with no special filters
