I wouldn't remove that brake booster section like the guy on the mkiv forums has...
The section of pipe he removed was connected through the PCV system and the vacuum drawing on it was produced from the TIP, hence there was always a source of vac on that line, whether at idle or under acceleration. And since there is always a source of vac pulling on that line, there is no chance an oil vapour, sludge, gunk etc can get into that part of the lines...
He's left the connection at the manifold and this will only be drawing a vacuum when either idling or under deceleration - the one-way valve prevents boost pressure destroying the vacuum.
I'd personally leave both hoses connected on the brake booster system
I run a catch can on mine and it is hooked back into the TIP to maintain the vacuum and
help scavenge from the crankcase.