breather smoke
breather smoke 
It is just oil that is getting hot going over the valve springs etc. The breather is just allowing it to vent into the atmosphere. Unless it is ALOT of smoke I wouldnt worry about it.
Does the car still have the PCV system installed? Is it does, then there is more blow-by getting past the rings than it can evacuate. If the PCV system was removed when you installed the breather, then that blow-by will just vent through any opening it can find. It is also doing a good job contaminating the oil.
