I think i have read many times about air filter comparison test especially in the Option Fans (Hong Kong) magazine. I think they should do it in different countries in the future. The smog in some big cities are hazardous. In the future, you have to use mini K&N filters inside your nose. Haha.
Izrin gave me this link which i have seen it before :
Based on the link, the only filter i have not tested yet is the Apex'i filter. Maybe i wasnt in luck to use it but im pretty sure im not going to use it since the physical effect after using it for quite sometime has the tendency to crumple like the K&N. Well basically all these filters were designed for maximum performance which means u have to change it every 5-10k kms, no shit.
Dont complain when you start to pay more for fuel and you only change your filter once a year.
As i told Izrin, i chose HKS was due to the fact its cheap to buy the element alone than buying an entire filter. Im thinking of long term and product availability. No bias in my judgement, cheap is always good. Haha.