I agree with MSantos.

The K&N filters flow capacity does not seem to be any better than stock filters, and can have a real down side with the oil used in the filter coating the Mass Airflow sensor and causing it to malfunction.

There is no advantage to low restriction 'lifetime" filters, and certainly items like cold air intakes, the Tornado, etc. do nothing but make your wallet lighter.

The days of miracle engine modifications is long gone.

 

K&N's suck. Just change the paper filter at double the recommended and it will flow just fine.

 

I agree with MSantos and Orient Express.

I OWN a K&N air filter. It *used* to be on my Mercedes Benz 560SL. Had a sensor fail in a short time, and the mechanic implied that the oil from the filter was a contributing factor. The filter's on a shelf now.
While it was on, the engine SOUNDED more responsive. I think that is ALL it was, though. And NO improvement in MPG, either. Bummer, because this beast could really use the improvement!

 

I've been using a K&N now for just about four months, and will also support to the "It makes no MPG difference" argument. However, in the *very* few places where I need to stomp on the gas, there has been a slight improvement in accelleration. For most people it's not enough to be worth it, and if it weren't for a couple of choice interchanges, I'd have also gone back to standard paper (and when I get my house in the country, I will). No problems with sensors, but then again, I haven't had to clean it yet. Nor have I had my first regular oil change with it in, so I can't make any "dirty oil" comparisons. Finally, the F5 dyno chart of their short ram intake does not impress me enough to consider modifying that, either. As the Volkswagon folks say, this thing's been "pre-tuned" for us.

 

+/- 4 hp is well within normal tolerances of a dyno, same car, same day, same setup....the intake probably did nothing.