The conical K&N filter and airtube setup is a very worthwhile mod, but it can be done many ways for a lot cheaper than the FIPK. I used to run Rusty's, and now run a 4.0L TJ airtube with conical filter on my YJ. I recommend Rusty's airtube and filter for an XJ. You will notice a difference, more power and much quicker throttle response. You will get more intake noise but nothing bad.