Best air filter
 

What is the best air filter? Been looking at the K&N Typhoon is there any alternatives to this that sit in the inner wing and aviod heat soak?

are you running a front mount? if not the best air filter is a panel filter in the standard air box.

Got a billet turbo and it cant get enough air through the air box

Green panel filters are good. What model's it for?

my03 sti

In my MY04 STI I had an APS wing mounted cold air induction kit[CAIK] Also a cold air feed from the fog cover provided cold air.
There are other similar CAIK's on the market aswell.
The standard airbox is very good but doesn't provide cool air although it is miles better than engine mounted CAIK's due to the heat build up.

OK. STi 04. Is it standard? If not, what are the mods. What power do you want to end up with?
The airbox on your model does not become a constriction until somewhere past 350 bhp but probably becomes a constraint before 400 bhp.