Since there had been some discussion recently regarding how well K&N filters worked and if they would damage anything, I switched back to the stock paper filter just to see the difference. I have the OSCAI setup and noticed that even with the paper filter, the OSCAI still gives you a noticeable improvement in throttle response and power. It does not have the same pull as with the K&N, but the car still pulls nicely at highway speeds and WOT. So, if you are reluctant to use the K&N, the OSCAI is still an effective mod. Although, a properly oiled and cleaned K&N filter should give you no problems....