Nothing screams performance like a set of dual exhaust pipes sticking out from under the bumper or roll pan of a late-model truck, and to be honest, nothing sounds quite like a dual exhaust setup, either. For decades, a dual exhaust conversion was one of the most popular modifications made to any truck: Just hop down to the muffler shop and cut up the stock system to make it a true dual exhaust setup.
Unfortunately, this approach has some drawbacks, including being illegal in several states. The other drawback is that today's fuel-injected engines require a certain amount of backpressure for low-end throttle response and torque. Eliminating nearly all of the backpressure with true duals usually kills low-end torque and often times makes the truck run worse than it did stock.
Designing an exhaust system that's compatible with today's EFI engines and actually makes horsepower and torque instead of losing it is the challenge most aftermarket exhaust companies face today. The dual exhaust systems of yesteryear have given way to more precisely engineered setups that use a single high-flow muffler. But what about the enthusiasts looking for that real dual exhaust look and sound?
The answer is found in DynoMax Performance Exhaust's line of bolt-on single-in/dual-out systems for late-model trucks. As an OEM replacement exhaust company, DynoMax has a history of making performance replacement exhaust systems for a variety of applications, from musclecars to late-model trucks.
The DynoMax GM dual exhaust...
The DynoMax GM dual exhaust setup we ordered came complete with the Ultra Flo muffler, head, and tailpipes, and even a set of optional stainless tips, along with complete mounting hardware and instructions. This particular system uses the stainless Ultra Flo muffler.
The company has taken all the guesswork out of one of the most difficult aspects of dual exhaust on today's trucks: routing the dual rear pipes around such obstacles as shock absorbers and spare tires. DynoMax's dual exhaust kit is a true bolt-on system that comes with all the necessary hardware, clamps, and instructions, so even a driveway mechanic can accomplish the swap. The piping is pre-bent, and the only real work is cutting the tailpipes to add the optional stainless-steel tips, since some trucks have roll pans and other have bumpers and tip placement is a matter of taste.
The heart of DynoMax's new dual exhaust kit is the muffler. The company offers three different mufflers for the kit, including the traditional turbo muffler, a welded Ultra Flo muffler, and a stainless-steel version of the Ultra Flow. Available in a variety of sizes, depending upon the application, the Ultra Flo is considered the top of the line in terms of performance because of its straight-through design for maximum efficiency and a high-flow rating. The Ultra Flo's CRF technology also produces a deep sound that is amplified and enhanced by twin tailpipes.
While the system sounds good and looks great, does it make power? To answer that question, we installed the new DynoMax dual system on a fairly fresh '03 Chevy Silverado fitted with GM's smallest V-8, the 4.8L. A trip to the chassis dyno facilities at K&N Engineering gave us some baseline numbers on the truck.
Then it was off to J-Sins B&M Mufflers in Corona, California, where owner Jason Garrett installed our system, which came with the stainless Ultra Flo muffler. Since the kit came complete with all the clamps and a pair of the optional stainless-steel tips, the install took less than an hour once we figured out which tailpipe was which and how it was to be routed around the spare tire and past the left-side shock absorber. The hardest part was cutting the tailpipes to locate the stainless-steel tips in the proper position.
With 300 miles of learn time on the truck with its new cool duals, it was back to the K&N dyno for some results. The truck picked up an average of 8 rear-wheel horsepower. It now also has that distinctive dual exhaust look and sound, and an OEM fit to boot.
 1. The heart of our DynoMax...  1. The heart of our DynoMax system is the welded Ultra Flo muffler. This stainless-steel unit features a straight-through design for more power and less backpressure. |  2. Here's what a typical late-model...  2. Here's what a typical late-model GM truck exhaust looks like. It's nothing special; just does the job of keeping the noise down. |  3. Since the stock system...  3. Since the stock system is basically one piece from head pipe to tailpipe, the easiest way to remove it is to cut the muffler away from the head pipe with a Sawzall. |
 4. With the muffler removed,...  4. With the muffler removed, the stock head pipe is unbolted next. |  5. The DynoMax kits uses an...  5. The DynoMax kits uses an OEM-style head pipe and flange that simply bolts in place of the stock one. |  6a. Once the head pipe is...  6a. Once the head pipe is in place, the muffler simply slips in place. Clamps that are included in the kit are used to assemble the components. |
6b. |  7a. The tailpipes are routed...  7a. The tailpipes are routed safely over the rear axle and around the spare tire. Both left- and right-side pipes provide plenty of clearance. | 
7b. |
 8. The tailpipes are cut to...  8. The tailpipes are cut to length in order to properly place the tips in the correct location. |  9. This particular kit came...  9. This particular kit came with the optional stainless-steel tips. |  10. The polished stainless-steel...  10. The polished stainless-steel tips feature the DynoMax logo etched on top. The company offers more than 12 different styles of tips to personalize your system. |
 11. On K&N's dyno, the truck...  11. On K&N's dyno, the truck picked up approximately 8 rear-wheel horsepower over stock. | | |