Yes we vented the sump tank for the turbo's into the breather as well. Open breather off PCV valve just doesn't work on the VQ motor. I had a small amount of consumption but not much (a little oil makes a lot of smoke). I don't remember the size of the lines off-hand. They weren't huge. The turbo's gravity fed to a tank under the trans/motor then a pump pumped it back up to the pan. I had a lot of oil when you let off gas after pulls (was like a mosquito fogger). After the catch-can there was zero oil. If you have oil at other times it may be more than a small amount of blow-by.
Tom
Tom