ok
a car engine run by the power burning of fuel + air
so every car hv a air intake system
but to keep the engine powerful and long lasting,
we hv fuel filter and air filter the filtering the dirts before entering the engine
so the concept is air filter must filter well the dirts

but nowadays ppl r looking for more performance,
traditional standard air filter is make of paper,
which filtration rate is quite good,
but at the same time the air flow rate is very low.
so to hv a good filtration air filter, we hv to sacrifice the air flow hence results in power lost.

so, aftermarket air filter brand develop air filter which is good in filtration, and also higher air flow rate.
famous among all the aftermarket brand was K&N and HKS perhaps
K&N is famous wif its long lasting air filter, which last for lifelong!
and HKS is famous wif its super high air flow rate,
but somehow some ppl claim tat its filtration is very bad.

talk about money value, standard stock filter need to be changed every 10000-15000km used.
for K&N, it last for life long, never need to change again. but of course u need to do some cleaning and reoil job.
if u plan to use ur car for long time,
change a K&N filter might save ur maintainance money as well

sry din notice about ur posting 

HKS hv high air flow rate on both Super Filter and Super Hybrid Filter