I have searched other forums on this subject to see why one would use one. The consensus was that it is used to separate the oil out of the pcv system on boosted engines. In the end it will keep the intake tract cleaner. Now my car isn't turbo yet, but by using a catch can/oil separator it would keep my intake manifold cleaner correct? Is the any particular design better than another? I know that a baffled on is the best.