Catch can designs similar to that of Mishimoto's have a proven track record of excellent filtering. The inside components are what I'm referring to....
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There are a few brands that share these same elements. I'm not aware of any other design being superior to the what's pictured above, in terms of air/fluid separation.
One more point - most blow by vapors will find their way through the PVC system, which is found on the posterior aspect of the passenger side bank. The engine also has another crankcase vent located on the driver's side bank valve cover, which is plumbed into the driver's side pre-turbo intake elbow. If you're attaching a catch can to both of these blow-by sources, it is best to use two separate cans, as each vent is utilized during different situations (ie WOT sees more venting from the VC, while partial throttle/idle sees most venting from the PCV system, thus the piping should stay separate between these two systems).