Well, I just got this shiny new turboxs catch can for my wrx, due to increasing blow by problems I have been having recently probably caused by a few recent mods but thats beside the point. I know I should be using two catch cans because of the fact that I have two valve covers w/ different pressures, but I'll take care of that later.

The thing is I opened it up and its empty. I used to have an NRG? I beleive one on my teg and it had something that looked like steel wool? on the inside, plus my boy has one that has some type of foam looking shit.... anyway, I talked to my freind and he told me to just stuff some steel wool in there, but is that really ok, seeing as how the catch can spits the air back into the intake before the turbo...... what can I use that is pretty much guaranteed to be safe? Thanks in advance.

 

That "steel wool" material is not really a filtering medium. It's purpose is to baffle and minimize moisture evaporation. What I did with mine is route the vacuum source from the exhaust pipe/downpipe instead to mimic a scavenge type system.