Unless you run the engine hard and hot you will always get somewhat of a smoke trail when you get after it. Its the particulates building up in the CAT and muffler then get flushed. That should be pretty dark and will dissipate quite fast.
The grayish black is typical of the Smarty and how it is working with the emissions setup of these engines. Sometimes you have to play with the timing settings to get the best setup for your truck.