Truck stacks on diesel powered trucks are very popular. This has become even truer, as pickup truck design changes make them look more like the big rig trucks that this type of muffler and exhaust system was made popular by. Truck stacks allow your engine to breathe more freely on the exhaust side, while still getting rid of most of the noise of combustion. They also look really good on the right trucks. This type of exhaust system is also available for trucks that aren’t equipped with diesel engines. The makers of these systems saw a demand from those who own gasoline powered trucks and they have designed and produced systems for those people.
For more info, see Info on Diesel Truck Maintenance