After extensive R&D we believe that this is the best diesel turbo back system available on the market. You will not find a system that is as free flowing, heat dissipating and gives you the dyno proven horsepower of this high quality kit. Each kit starts with a 4'' down pipe from the turbo into a 5'' expansion chamber and then into a 5'' double wrapped straight-through core performance muffler which then exits in the stock location. Recommended only for trucks that have a power programmer/chip and a free flowing air intake or filter.