A cast burn down breather has a Z baffle inside and can be bolted on top of the valve cover. I've yet to find anything as effective at this job as them.
Goodvibes, and rbs has them and they come with the base gasket, and the outlet is threaded for an oring AN. They look a bit out of place on anything but a hemi, but work like magic.

http://www.rbssuperchargers.com/Products/Burn_Down_Breather_Set_Polished_Thread_In_Hose--2600-0008