Dual Exhaust Vs. Single Exhaustby Bud Maxwell
The internal combustion engine takes in air and mixes it with fuel, which provides the perfect combination for the explosion that fires the pistons. After that explosion takes place, the remaining gasses are forced out of the engine via the exhaust manifold. Increasing the amount of exhaust gas that leaves the engine has a direct influence on the air intake, and can significantly increase torque and horsepower.
Most new cars come with a single exhaust system as they are cheaper to make, and for most people the difference between a single and dual is not important. The purpose of any exhaust system is to channel unspent engine gasses through the exhaust manifold and into the atmosphere. A single exhaust is not only the cheapest to build, but it is also the most restrictive, cheating a car enthusiast of readily available horsepower.
If your new car came with a dual exhaust, it's because the auto maker designed and advertised it as a high-performance machine. Muscle cars of the 1960s and 1970s all came with dual exhaust. Don't be fooled, though, as some dual exhaust systems are actually single exhaust, as a few manufacturers use just one manifold and split the exhaust pipe after the muffler. From behind the car you see two tailpipes, but if you follow them forward, you'll find just one pipe and one manifold. There is no horsepower advantage to a system like this.
An important part of any dual exhaust system is the header. Headers replace the restriction exhaust manifold and bolt directly onto the engine. These non-restrictive tubes feed exhaust gasses into each tailpipe, one of each side of the engine.
Each car is different when it comes to how much horsepower one can expect from the addition of dual exhaust. Most manufacturers of aftermarket dual exhaust systems claim an increase of 15 to 20 percent in horsepower (hp). A car producing 190 hp, for example, could potentially see an increase to over 225 hp, an impressive gain. Adding headers generally adds another 20 to 20 hp.
As with anything, cost is relative. One must ask the question: is the increase in horsepower really worth it? That all depends on how badly you need more horsepower. Owners of the notoriously underpowered six-cylinder Jeep Wrangler often complain they have to down shift to climb even shallow grades or to maintain highway speeds. In their case, investing roughly $1,200 for a certified mechanic to install headers and a custom dual exhaust would probably be worth it. Before deciding on any system, however, it is always wise to talk to several mechanics for their expert opinions.