Fuel Injection Performance Kit
This is the cone air filter that comes with the kit. As you can see the heat shield doesn't go all the way to the fender and hot air and mud can get to the filter. It's probably a good idea to build some kind of shield under the filter since the the shield that comes with the system doesn't go down to the fender, I've had a little dirt splashed on the underside of the cone filter and it was hard to wash off.
Some people worry that without the shield the intake sucks alot of hot engine air which lowers the amount of power you get from the engine. But every time I clean the filter the dirtiest part is the side facing the fender. It's pretty obvious that most of the air the intake takes in is coming from the holes in the finder that the original intake sucked through.
Some people have had complaints with dust getting past their filters but I've never had that problem the whole time I've used K&N filters so all I can figure is that they've installed their filters incorrectly. Others say that they can see light through their filters but the way the filter is made light can pass through the oil and bend around the fibers, like a fiber optic wire made of gauze and oil. Paper filters do catch more particles but they are alot more restrictive, nothing big enough to harm your engine will get through the K&N.
Go to this link to see my additional FIPK mud shield.