I bought a crankcase evacuation system that welds up to headers a few years ago, and never got around to putting it on because my mopar valve covers didn't have the right hole. Now I'm feeling less lazy, and will drill the hole I need for the breathers. I've read, however, that running the evac system with Flowmasters (chambered mufflers) will cause backpressure at higher rpm which can counteract the vacuum I want, and actually pressurize the crankcase. I've read several forums, and it seems hit or miss. Anyone have experience with this? Right now I'm running regular twist in breathers that like to leave a few drops of oil on my valve covers after a full weekend of racing. My main reason for this is to maybe gain a little power, but I will not sacrifice my mufflers. Maybe an evac system won't do anything for me, I don't know, but this is why I'm asking the professionals here.