Thanks Wiz...
I already tried it without the oil separator pot and it still smoked. Breather system is triple-checked and fine. Smoke is blue and smells very oily. I'm positive I put the rings on correctly, as an expert showed me how to do it on one piston so I could do the other three myself. I took the head to a shop to have the stem seals replaced and to have it checked in general and they found no problems...
So you think it's not turbo-related then?