Route crankcase breather after air filter?

On mine, the oil separator catches the oil & it falls to the bottom of the separator & fresh, clean air go to the intake. It works awesome. You do have to drain the separator of oil once in a while though. Worth the money & effort. If you do the closed system, (mounting the crank case breather after the air filter, you should filter that air too. There will be some oil in that air. kursplat has a good suggestion.