I noticed black oil particles on the ground near the exhaust after startup. The car does not smoke and the boost system has perfect pressure. The car runs great. Is this a turbo seal problem coming from the exhaust side of the turbo?

 

probably soot being blown out the exhaust. you get some condensation (ie water) mixed in with deposits and you will get that. Park next to some diesel truck with exhaust pointing out and you will see it all over your car when he starts up.