[Trackrash]

It always comes down to compromises, just like anything else that is engineered.

Stock is good, filters small particles.

K&N maybe not as good eliminating small particles but on the other hand has less restriction to air flow. You will have to clean and oil them periodically however.

You could gain a couple of HP with the K&N, but is it worth it on a stock motor? On a modified motor you may realize a noticeable improvement in power, like I have with my car.

K&N was originally designed for dirt circle track cars. Were later adopted by the off road crowd. Of course those guys didn't expect their motors to last 100K miles.

If you are not driving in dusty environments IMO K&N is just fine for a street motor. I have used them for decades on both of my air cooled cars with no noticeable ill effects.