I have a little black smoke from the exhaust when I start off. The lighter I push the gas pedal the less the smoke. The more I push it the more smoke. Its not like tuner smoke you see from these teenagers but it is noticeable. The truck runs good, no loss of power,etc. Whats your opinion on the cause and is there anything I can run to help it out or is it just a Cummins things. 163,000 miles on it. All stock except for exhaust. I have heard the Hot Shots works well.