Bully Dog's Rapid Flow exhaust systems are a great way to reduce your diesel's exhaust temperatures while increasing horsepower and economy. These systems boast the lowest-degree mandrel bends around, thereby promoting a free flow, resulting in more horsepower and torque. In towing situations, these low-backpressure exhausts lower temperatures by as much as 200 degrees and provide a 10-20 hp gain, depending on the size of the upgrade and the current horsepower output.