I see these modern big diesel pickup trucks ROLLING black smoke under acceleration. I mention modern to indicate they aren't old beaters with engine issues. These trucks are tuned to do this...why? What is this about? Do you really get better performance in a road vehicle doing this? We aren't in a tractor pull on I35 folks. Oh and the stacks coming out of the bed? Well, those I can live with if you don't emit coal colored plumes of smoke out of them, but still!