I am doing a review on a conical air filter by K & N. This company has quite reputation in the car industry, and they actually market their products as "The Worlds best Air Filter". I must say they are right - probably.
The idea of filtering the air before it goes into your engine, is a very sound one, and it makes sense to use a high quality filter, so far so good. But, the problem starts when paople remove perfectly good factory fitted filters, and replace with some sporty so called "Improved" aftermarket version. If we use my car as an example, the air was fed to the standard air filter, through a section of ducting, which is routed al the way to the front grille. This means that the air will be at ambient temp. OK, fair enough, it is a good system, but the cone filter I was bought is designed to be fitted instead of my old panel filter, inside the engine compartment, where the air is warm. There is no ducting, the air is just allowed to circulate round the engine bay, then be sucked into the new Improved" filter. This means that the air being fed to the engine has been warmed, and so will expand less upon combustion, meaning of course WORSE performance!
I do appreciate that the filters are very good, and they are very cost effective because they require cleaning, and not replacing, but after a while, I found that the most practical scenario, would for me to actually fit my K&N filter, inside the old airbox, and retain the old ducting, providing fresh cold air to the system. I am well pleased with this solution, but feel sure many customers buy these High performance "Designer" filter for their looks, so don't want to hide them away inside some old plastic box.
The effectiveness of these filtes is very good, and they do filter out more dust than many standard filters, I have nothing against them at all, but thenet time I fit a K&N filter, I will be a high perfeormance panel filter. Nobody will see it, it will be more efficient than my old original equipment factory fitted one, and it will save me money by not needing rplacements.
There you have it, my own opinion on these filters, very good, but you have to think what you want.