I agree with Porsche-O-Phile - K&N is more hype than a Fram oil filter.
I used a K&N filter for about 3 months on an older 4Runner ('85) that I used as a daily driver and for off-roading. I needed to pull apart the intake for some reason and found a thin layer of dust and grit inside the intake that was not there previously. I cleaned out the intake and switched back to a stock filter - no more dust or grit in the intake.
K&N's do flow better, but I would argue at a cost. The amount of crap those filter let through are more than I'd want in a $500 Toyota engine. I can't imagine why you'd want that on a $5000+ engine.
To further my point, my 911 came with a K&N installed - looked brand new. I tossed it. Those that know me, know how limited funds are for me. It litterally takes me months to save up for basic parts for my car. I often end up selling other belongings to fund Porsche parts. However, rather than re-selling a crap product and contributing to the destruction of someone else's engine and adding $20 to my pocket, I chose to put the K&N where it belongs - in the trash.
I'm amazed with all of the in depth analysis that has been done on these filters, that people still insist on putting them in their cars. If you have one, go hug your engine, it may be the last chance you have.
