Okey-dokey, here's my review of the K&N replacement filter, which I finally got around to dropping in over the weekend. Yes, it makes a difference. As expected, there isn't a huge horsepower increase, at least none that the seat of my pants could detect. But as Tony mentioned, throttle response is indeed quicker and the car seems to pull a bit better. More importantly, the engine seems to be a bit smoother than before, presumably do the fact that the K&N is supposed to straighten/smooth the airflow. That's about all I have to say - take it or leave it. I think that spending $55 on a filter that is guaranteed for a million miles and can be washed and reused numerous times is a worthwhile investment. Andrew "EL-e-Mental" B. 97 EL Sport, primrose, 25K