It’s rare to find a collection of bolt-on parts that actually work in harmony and build additional horsepower and torque from an engine, let alone find them all under one manufacturer’s banner. Over the years, OFF-ROAD magazine has tested all manner of parts combinations, each one taking a different approach to enhancing a stock engine; some worked and some didn’t. This time, we went to the source of diesel-engine performance, Gale Banks Engineering, and struck gold. Not only did it take one stop to buy and have our parts installed, but the parts worked as advertised and the results were awesome. In this article, we had Banks outfit Duramax diesel engine-powered ’03 Chevrolet 3500HD Crew Cab pickup with the company’s PowerPack® system. The PowerPack included a new air intake, a free-flowing stainless-steel exhaust system, a computer upgrade, and a new turbo wastegate. The collection of parts improved the performance of the Duramax engine, and a Banks exhaust brake system aided in downhill braking situations when towing a heavy load. Once the systems were in place, we headed to the highway to see what improvements were made. We went to a familiar section of the freeway with a loaded car trailer and proceeded to haul but straight up a grade without our truck even giving off so much as a whimper. Acceleration definitely improved, and the motor was obviously making more torque. On the downhill side of the grade, the Banks exhaust brake worked perfectly, slowing our rolling convoy down without us having to lay on the primary braking system. The numbers generated from Banks Engineering’s chassis dyno served to cement our observation that this truck was definitely making more power. In short, the installation was involved, but the parts worked and we were happy with the results.