First of all, I'm definitely not an expert on this subject but what I got out of it by talking directly to Tracy at RevExtreme, due to the nature of Direct Injection oil ingestion through the intake causes a build up of oil on the valves. Overtime it builds up and causes problems with the valves. The catch can and clean side separator redirects about 90% of the ingested oil to the catch can where it can be drained periodically instead of having to deal with valve build up. Without this setup only about 30% of the ingested oil is removed where it is burned through the exhaust system. It sounded plausible to me and, as I understand it, they are installed at the factory on the "go fast" Camaros which made me decide to get one. Does it work?...I don't know but I figured it couldn't hurt.
If you want the real skinny on these catch cans/clean side separators call him (Tracy) at 941-721-1826, and ask him directly. He can explain the whole concept much better than I can. But, like I said, it made sense to me.
I hope this helps.