The cam cover pressure should be pretty much atmospheric,using this sort of cover,and my crazy Romanian friend has one of these on his 700bhp Golf,so I think it should be OK.
i really need to stop listening to that workshop of mine (near the one year mark in 2 months by the way )... though i don't know how good this will be as the oil breather system is being deleted on mine for a 1.8t set up