on the whole system starting from your filter(intake) When you are driving the car you will not have pressure in the intake, pressure will start building after the turbo. When you put pressure starting from the intake you will put pressure inside the engine because there are pcv hoses that go to the valve covers from the accordion pipes. You main problem is to make sure it dont leak oil form the covers. I am guessing you have a TT your profile dont say anything but its about the same thing on NA.