I had the same thing... took in for an oil change... replaced PCV.. still leaked and then got the Manifold replacement story $1600AUD part + Labour... told them to clean it up a bit and not replace as I am getting rid of the car soon... I think the bit about the swirl flaps is only applicable to the E53 when they use metal flaps , but not sure ... am taking it to an independent to see options shorlty.