I think pretty much everything under the hood has a good purpose and none of it robs any power. :dunno:
blow-by is a whole nuther issue. make sure the skinny line going to the valve cover is cleaned out. The late model valve covers can help out too. they have a different baffle system inside.
oh, and the 4.0 is not a PCV, it's a CCV. there's no PCV valve, just an open elbow. :thumbsup: