[Heiko]

Swapping the pumps is only a test and doesnt remedy the fix for the damaged pump! If swapping the pump reduces the smoke under load then the pump that originally came from the right side needs to be replaced.
The problem is that the right side extractor pump sits at the rear with its vent hole directly above; and the left pump is at the front. So when you accellerate hard (and even worse if you accelerate and turn left at the same time) the oil flows to the rear of the head rapidly... if the pump is weak or not functioning 100%, it cant return the oil to the sump fast enough and it gets sucked into the AOS through the above vent.
Under normal driving, people braking hard and reving high RPM's isnt likely, which is why on the left side the chances of oil getting sucked into the front vent is less likely. Now having said that... If you track your car you'll probably find that you will have no choice but to install a bigger AOS unit to handle the extra oil or even go to the extreeme and install better oil return pumps.
H