Wow, as it comes time to sell my 06 MPS soon, I've had the same issue. Smoke from unburned oil billowing out the back when turbo pressure hits. Filling the oil on a regular basis to. Started happening when the timing chain and oil pump chain were replaced. Of course the coincidence won't be accepted by the mechanics.
I've had the PCV valve replaced, no dice. Guessing the valve seals might be on the way out. Catch can will only be a band aid fix I'm guessing.
I know this is resurrecting the thread, but what happened in the end Byrd? Did you end up having the top end re-done or complete engine?
3 MPS - Rolling on Pirelli PZero Neros, sitting on Bilstein B12's, stock internals... still makes me smile with the Zoom Zoom.