As has been stated, if the engine is sealed well and the vac relief valve (if used) is in the correct position you should draw very little oil.
Actually it's more moister than oil(e-85 fuel)I'm running a Moroso catch can with the baffle at the top. Most cars i see at the track has some sort of rag that's rap around the filter area to catch the excess oil.
I was looking at Motion works catch cans and they clam to not have this problem.