First, this was a new truck, and that was bound to hold back gains to some degree. Second, how much you gain from either improvement (or both) is directly proportional to how well or poorly the original systems flow according to the engine's true needs. That means the results on an otherwise stock engine can run from so-so to significant. Remember that power and torque are all about a mixture of air and fuel. The new intake and exhaust let the engine develop a few more ponies from the stock programming, and that's a good thing. Without more fuel being introduced, more boost, and changes in injection timing, that was the end of the gains.
Among the hidden benefits of high-flow intake and exhaust systems are lower exhaust gas temperatures (EGTs). This is especially important to a towing truck grinding up that long grade with a heavy load. Every degree of cooler air going in results in EGTs cooler by that same amount. A free-flow exhaust also offers cooler EGTs, and the bottom-line benefit is that you can safely run your truck just that much harder with both of those mods, even if the power output is only mildly enhanced.
The ATS TorquePro 2000 is an on-demand propane-injection system that's actuated by boost. It mounts under the hood and needs to have coolant hoses run though it to warm and vaporize the incoming propane. The propane is not inducted under pressure, but is drawn in by the engine airflow from a low-pressure vapor line. Two very important considerations are where the inlet orifice is placed and the length of the vapor line, which must be less than 3 feet long. An adjustable boost switch is used to activate the unit, which also has an on/off switch. There are several safety interlocks to prevent propane from entering the engine before the correct moment. | 
The size and location of the propane tank is somewhat optional. The type of tank is not. It must be a liquid-draw tank certified for vehicle use. Many people mount them on the framerail as shown here, but take care to locate them at least 19 inches from a major heat source, or behind a shield. Some use bed-mounted tanks, which is also OK. Special propane hoses are used, and all connections should be leak-tested prior to operating the vehicle. In addition, the hoses should be solidly secured every 24 inches. | 
Placement of the fill valve for the tank is also optional. In this case, the class installed a flip-down license-plate holder on the back bumper and located the fill behind it. |