ach ich vergaß! 
It is the valve cover breather filter.
Adding just a filter is rather a bad idea for a NA motor. You would now induce humid air into the motor as the PCV system is supposed to be sealed. The location that this filter is located at, is supposed to see a draw from the intake, applying a small vaccum to the valve cover. Thusly the addition of this filter is having the same affect as creating a vaccum leak(down thru the oil drains in the head, thru the block,the PCV valve and directly to the IM).
If you have a oil seperator/catch can between the PCV valve and IM you will find the oil in it all foamed up, with a pale chocolate color indicating moisture in the motor.
This is all from first hand experience.
I wanted to post this up as I seen two cars today with this cool looking filter installed and could see this becoming a "cool cheap mod".
And yes I had one of these cool filters installed for all of 20 minutes.
The majority of vapors go OUT thru the PCV valve, and a very little from the valve cover breather tube(only at high rpm's).
There is a vaccum applied by the intake to the VC and as the crank rotates there is a pulsing action exerted onto the air at the VC. The heated tube warms the air pulsing there to prevent condensation from forming inside the motor. The vapors, along with air drawn from the intake are drawn thru the motor, out thru the PCV valve and into the intake. If there is no resistance applied(from the intake) to the air from entering the VC then the air goes straight thru the engine block and out thru the PCV valve. Creating a vaccum leak you will not hear.
Without a even a filter there you will allow all sorts of CRAP to be drawn into the VC, add some oil and you are now wet grinding all the mechanicals in the head!!!
It is your engine to destroy, I am informing others to not make your mistake. Hook up Kpro and check what your MAP is reading without the VC connected to the intake and then check it with it installed and you will see the difference.
Proper crank case pressure is required for the rings to seal and wear properly.
I would imagine that another side affect of the filter would be some added oil "consumption" thru the PCV/IM.
I would add a catch can and plumb it in between the filter and compressor.
With a NA motor at least, having this line from the VC to the intake disconnected will cause a vaccum leak as you change the volume and speed of the air going thru the intake/motor. Almost like a stumble or a feeling of being restrained/held back.
so bin leider kein pc genie drum hab ichs auf dem easy way gemacht!
