You *could* just buy one from ebay (many do) and then mount them infront of the accessory drive. The issue is the ATS has a convoluted and honestly hideous PCV system and it just doesn't do an amazing job at what it's intended to do, and I'd be wary about coming up with your own hose routing/connections without searching the threads to find out how others have routed it all.
No...internal baffles in the cam cover. We suspect the rear PCV valve is the culprit. But, only under certain conditions. I have a check valve installed in the air intake line and I hear a silght whistle for about 3 seconds when I shut the engine off.
OK , did some messing around. It is the rear pvc making the noise, you are right oemtech. Ended up getting a cel already and fuel trims were way high. I did some tinkering and used a nitrous jet on the vacuum side line by the throttle body to restrict vacuum, .040 jet trims were close to stock, .080 jet could hear the whistle. Ended up using a .060 jet and trims very close to where they are with line capped off, and very faint whistle noise . I will test this for awhile see how it is.
Atrim, if you put a vacuum gauge on the line going to the air intake in stock config you will only see maybe .5 psi of vacuum. Not sure what it would be at hwy speed and under boost. But, I bet it would be much higher. So, my theory is the mist is re-circulated at low vacuum and mixed with fresh filtered air via the front PCV valve. But, under hwy speed and boost the mist is sucked into the air tube and into the turbo. I base this on oil in the white silencer and the intake of the turbo. I added a check valve on the air intake so no mist can go to the turbo but fresh filtered air can go to the engine.
Did some more messing around with this again today and hooked up all pcv's to the catch can, and made a vacuum tee restrciting vacuum so the whistle noise is minimal but still has vacuum on all three pcvs.
Started off with a 3/8" brass tee fitting at the evap solenoid line for the idle and low throttle vacuum
Took a nitrous flare jet and kept increasing the orfice until i just started to hear the whistle from the pcv valves. Ended up drilling to a .067
Took the jet and tinned the jet and end of tee fitting with solder and soldered them together to restrict the vacuum to the pcv valves to reduce the noise and fuel trims. Fuel trims however i can re tune with HP tuner.
Used a reducer nylon tee fitting that is 3/8" through and 1/2" off the side to match the existing line size going to the pcv valves on the side of the valve cover.
I'm not saying this is the right way, but it helped. It has more vacuum at idle than it does from the factory so i'm sure it helps with evacuation. Hopefully Tracy figures out something or this helps with a final solution. I don't normally drive this car but cant wait to see what the catch can traps in it.