First I started working on the power to my XJ. The first thing was adding the K&N FIPK. It gave it a cool sound, as far as power gain, yea I guess alittle, probally all in my mind though. But you can definately see the increase in gas mileage before the intake I was getting about 320 to a tank after the intake it went up to 400. I also added the nylon wrap they offer, there is ALOT of dust in El Paso, every little bit helps. I still like the K&N kit but cleaning the filter is a PIA!