I asked the guys on the TRMA about how much smoke Titanic should have, and at first, Bruce Beveridge replied saying that Ship Simulator 2006 had a more accurate amount, but then Scott Andrews replied later, saying that even though some ships occasionally have heavy amounts of smoke coming from their funnels, and that it is good for dramatic effect, in reality, less smoke is more accuate, as if there is heave smoke, incomplete combustion is occuring, which means wasted coal and cash.
So, despite popular opinion, less smoke IS more accurate after all, as that much smoke would not be released unless the boilers were really being forced.