View Here : Powerstroke Exhaust Brake
Control your down hill acceleration with a BD Diesel Electronic Exhaust Brake. Using three different braking modes, the BD Diesel Electronic Exhaust Brake closes the turbocharger vanes during deceleration causing the engine to retard and slow down.
An exhaust brake is simply a large butterfly valve in the engine's exhaust stream. When closed, the exhaust brake traps a great deal of the engine's air inside the cylinders. The engine continues to function as it normally would, but gets only enough fuel to idle.