Note the cones visible inside the muffler, which are said to be tuned to create excellent flow and a performance sound. They will not burn out like glass packs or mufflers of lesser quality.
Installing the Exhaust
Using a vehicle lift, the Hushpower exhaust system install took about an hour, including the time required to take pictures for this article. The hardest part was removing the downpipe that attached to the turbocharger. The key was not to damage the coupler, and make sure the new downpipe was attached correctly. All of the original rubber hangers were reused in this install, and because of the low mileage on the truck, none required replacement. If your truck is older and the hangers are not in perfect shape, they should be replaced.
Programming Power
For our test, we also used a new Superchips Cortex programmer. This is Superchips' newest programmer for the LBZ Duramax. The programmer comes with a two-year drivetrain warranty and features three levels of performance upgrades. By simply plugging the programmer into the data link connector under the steering wheel, we could select either a Tow performance setting or two additional higher power levels. The programmer also retains the original computer program features so that the stock settings can be reinstalled. All three of the performance levels were tested at the Westech Performance dyno facility.
The Hushpower exhaust kit included all of the tubing, hanger hardware, and complete instructions.
The Results
Our dyno testing proved a number of things right off the bat. The test with the Hushpower system alone netted a 13-lb-ft increase in torque and 7 more horsepower. The important part of this change is that the free-flowing system raised the performance potential for the programmer upgrades that would come next.
When the Superchips Tow performance setting was uploaded, power jumped from 601 lb-ft with the new exhaust to 656 lb-ft. With the Level 1 performance program uploaded, that number jumped to 723 lb-ft of torque. Finally, the Level 2 performance program was selected, and it generated an amazing 743 lb-ft of torque at the rear wheels, a full 142 more lb-ft than the stock truck made with the Hushpower exhaust.
Here is the factory muffler for comparison. It was fitted just ahead of the rear axle in this application. | 
To change out the system, this bracket had to be removed. The complete system was installed in less than an hour. | 
The factory downpipe (right) featured a resonator and these flow-restrictive bends. The Hushpower tubing is much straighter and freer flowing. |
The original hanger points were used. | 
Paul Gonzalez installed the downpipe on this truck. Making the connection to the turbo was critical to this installation. | 
The Hushpower mid-pipe fit in this location. An additional hanger point was supplied as this piece of tubing is used on the various wheelbase and cab configurations that GM offers. |
As with all the tubing connection points, the Flowmaster (Hushpower's parent company) stainless steel tip slides in place. | 
These grommets kept the rubber insulators in place. Don't forget to reinstall them. | 
The Superchips programmer included the connection cable, which fits to the data link connector under the steering wheel. |
The Westech Performance crew strapped the '07 Silverado 2500 to the dyno and performed the chassis dyno testing. The sound of the truck with the Hushpower system installed was far superior to the incredibly quiet original factory system. The power numbers were equally impressive. We achieved an increase of up to 142 lb-ft of torque in the Level 2 setting. | 
The programmer walked Gonzalez through all of the requirements needed to reprogram his computer. The instructions were very easy to follow. | |