That's a scavenger system that must be installed on the exhaust down stream where there is no back-pressure.
I installed one (E vac Scavanger) on my ALH engine in the Vanagon. I initially installed it pre-CAT and it would not "pull" vacuum. In fact, there was back-pressure. So, I relocated it post-CAT but before a straight through glass-pack. The CCV vapor does not go through a catch-can nor is there any smoke that I am aware of.
Here are a few pics. (Remember, this is in my Vanagon, engine in the rear.)
Below, you can see the stainless steel braided hose coming off the CCV puck ..
Below, around the end of the engine...
Below, you can see the E-vac pipe between the CAT and Glass-pack on a 45 degree angle which is by design/function.
Below, is a shot looking up the exhaust system...
It is actually designed for the 45 angle cut to be pointing down because it has a cut on the back side that allows exhaust to enter creating a vacuum on the hose. However, that little hole will become clogged with soot and oil. So, rotating the 45 degree cut pipe as I did, eliminates clogging and works just fine as well (over 80k miles with no problems).
This link provides a close-up of how the pipe is cut...
https://www.amazon.com/Vibrant-11189-E-VAC-Scavenger-Kit/dp/B002USFCV2
EDIT: I remove the pipe (very easy to do) every other oil change to make sure it is clean and functioning properly.