GMC Sierra 2500 HD / 3500 HD Duramax 6.6L 2008-2009, Black Aluminized Steel Diesel Downpipe by MBRP®, 3" Diameter. This large-diameter downpipe is the ultimate in free-flowing exhaust. Connecting directly to the turbine outlet, it makes minimum-radius bends for the best flow possible. Don’t let a small-diameter, convoluted downpipe that was engineered for low price and easy production-line installation be the choke point that keeps your engine from making decent power.
- 4" diameter throughout, with smooth, constant-diameter bends
- Shortens turbo lag
- Improves economy
- Boosts power and torque
- Complements other performance mods
- Maximum flow
- 16 GA Aluminized steel
Exhaust backpressure costs you money, because it takes energy to push exhaust gases out through the tailpipe, energy that comes from the diesel fuel you’re paying through the nose for. It also costs you power, because any residual exhaust gas left in the cylinder prevents fresh air from being drawn in on the intake stroke. This massive downpipe attaches to the most important place in the exhaust stream: right after the turbine outlet where the gases are expanding fastest as they cool off on their way through. The pressure and temperature differential across the turbine are what extract otherwise wasted heat energy and use it to pump more air into the intake.
Fifteen years ago, MBRP® started in the exhaust business by introducing the B&B Eliminator, a silencer that quickly became the best-selling snow machine muffler of all time. Exhaust system technology being as universal as it is, they soon branched off into cars, Jeeps, and diesel trucks, with amazing success. One of their secrets has been the practice of making as many universal-fit kits as possible. A couple of extra parts in the box means that a single kit might fit a number of different wheelbase pickup trucks, for instance. Reducing complexity in ordering is better for them, better for their distributors, and a great benefit for their customers, who are more likely to be able to find a kit that fits their vehicle on hand. In addition, they go to great lengths to make sure their systems fit properly every time. Careful attention to design and fabrication delivers a system that doesn’t need customization with a hammer to fit properly before the car or truck comes off the lift.