Al, no disrespect, however the breather has everything to do with the PCV valve. When vacuum goes low, PCV opens. At this time the breather is passing air into the valve cover-thru crankase, and up thru intake via the PCV.
This is air entering the intake path, it is part of the combustion, and, since it is during low vacuum, (acceleration) this air must be metered.
Also, during acceleration, some blowby will occur. the breather filter in line with hose will keep some oil out of the intake tube ( like you had it before)
You might ask Doug about this "metered " air thing. I am sure it is important.