Best air filter

[L_O_O_M]

Hi all



I was wondering from you guy with experiences what is the best air filter to use in terms of best filtering,flow....etc?What material is best,what shape,does shape make that big of a difference,will one large round air filter like the ones they use on trucks work better in terms of filtering and flow.....etc if you have a turbo or N/A engine? Because I have seen some scary filtering test with big name brands that almost doesn't filter any dust and a friend developed engine trouble because of an cone air filter he put on his truck and didn't filter correctly.