Hi guys. I'm a regular over on the Greek board, but i would like an advice from some guys with good technical knowledge. I

 

You might want to keep an eye on this recent thread.
https://www.s2ki.com/forums/index.php?showtopic=344875

The fact that your coolant level is staying the same would indicate that it's not steam you seeing in the exhaust smoke. With your level of oil consumption, that would be the better guess. Also, you would have a higher than average rate of carbon and soot deposit in the exhaust, adding to the smoke when you increased exhaust flow.