What N Lee is referring to is simply routing head breathers to the atmoshpere. This modification is very common and there are several ways to make the mod via kits from vendors like Trask, Doherty, DK Customs, etc. DK Customs is a popular supplier of these kits. DIY is ususally cheaper and easier to "personalize" for different applications, i.e., hose type, filter/catch can and routing. Anyone on this forum runnng OEM breather setup should consider this modification. Take a look at the attached photos to see the difference between internal and external venting of head breathers. Also attached is a photo of a DIY version of this mod; head breathers routed through crank vents to a small filter.