I put mine in a couple of days ago. Not sure on the gas mileage yet. I'm not sure but I think I can feel just a tiny bit of perfomace when I mash the gas pedal. I'm sure it's doing some good though. Maybe just on principle
From what I have read about K & N filters on other car sites it appears that the filter is better at cleaning the air and letting more air in which is suppose to increase performance and MPGs. The materials are better so they of course cost more. Right now you can not find a K & N filter designed for the El so I thought perhaps the CRV would fit. Chuey did you use a CRV air filter?
I have a K& N on my current truck. Installation involves the removal of the entire filter housing. The K & N then attaches to the hose where the OEM was. It is a cone shaped filter, so unlike the original, air can flow in from all directions. I noticed improved pedal response and a 1-2 MPG fuel efficiency jump in my Jeep when I installed it. Also, you never replace it, you simply add a cleanser to a bucket, and immerse the filter in it to release the dirt it's collected. It costs more up front, but in the long run its a better deal, plus no waste. If the CRV one fits, it's worth the money. The only downside to it is that you get increased engine noise, but I kind of like the growl!
The installation is fairly simple and straight forward....atleast in a Wrangler. The stock box removal involved only a couple screws, and a bracket. The K & N assembly just slipped on the hose going to the intake, then bolted in to the space where the box was, using it's own braket. I had to drill a couple holes in the engine compartment, but they were away from everything, and hard to screw up. Overall, the install took a half hour, maybe 45 minutes. Here's a link to the CRV filter for a price reference. http://performance.performance-air-filters.com/
Be careful with K&N's. The main reason you get higher air flow is that there is less resistance thru the element. This generally means decreased flow restriction which in an air filter means more air, and consequently more fine particles getting thru the media. I researched this topic extensively a few years ago wrt racing motorcycle engines. Many people shy away from these types of air filters for everyday-type driving as a precaution. I'd stick with the stock Honda filter for everyday driving; K&N's if you're going racing. Just my $.02.