EXHAUST SYSTEM COMPONENT GUIDE

A good exhaust system is much more than plumbing; it improves the performance of your engine, enhances sound, and makes your ride look great from behind. If you're looking to upgrade your factory exhaust, you should understand how each component works and how they all work together to maximize your driving pleasure.

	EXHAUST HEADER The exhaust header is a tubular bolt-on replacement for the stock exhaust manifold. Exhaust headers consist of three, four, or six header pipes of equal length, one for each combustion chamber. The header pipes join together at the collector, which bolts on to the rest of the exhaust system. By replacing the small-diameter, restrictive openings of the stock exhaust manifold with smooth, larger-diameter pipes, a header allows a larger volume of exhaust gases to exit the combustion chambers more quickly and smoothly. A well-designed header also improves exhaust flow by actively scavenging exhaust from the cylinders. Scavenging is the process of using the momentum of exhaust flow from other cylinders to create a slight vacuum that draws the maximum amount of exhaust from each cylinder. Most headers are available in stepped (4-into-2-into-1) or straight (4-into-1) designs.
	CATALYTIC CONVERTER One of the most important emissions-control features of any street car, the catalytic converter is a passive device that consists of a passageway with a ceramic honeycomb structure coated with a metal catalyst (such as platinum). When superheated by the exhaust flow, it reacts with pollutants such as carbon monoxide, volatile organic compounds, and nitrogen oxide created during the internal combustion process. Catalytic converters are amazingly simple and effective, but their restrictive nature can be a major drain on performance. They also tend to become less efficient over time, decreasing performance even further. Aftermarket units, commonly called "high flow" catalytic converters, are a good compromise between the emissions-management features of factory units and the performance characteristics of an (illegal for street use) open exhaust. Because high-flow cats inhibit exhaust flow less, they are somewhat larger than stock units. The most effective aftermarket cats are constructed of special alloys that retain heat well, thus making the most of the short contact time with the exhaust flow. Even though you might be tempted, under no circumstances should you run your car without a catalytic converter! In fact, you should check your local emissions laws before purchasing a high-flow catalytic converter.
	CAT-BACK EXHAUST SYSTEM A catback system is any aftermarket product that carries the exhaust flow from the catalytic converter to the back of the vehicle. Cat-backs typically include a muffler, exhaust tip, piping, one or more resonators, and mounting brackets for a particular application. Many cat-backs feature dual exhaust, in which there are two mufflers and exhaust tips. Cat-backs are available in mild steel, stainless steel, and titanium. All three metals offer the same performance characteristics, but differ greatly in looks, durability, corrosion resistance, and price. Choose mild steel if you're on a tight budget; choose stainless or titanium if you live in a wet area or drive your car in winter conditions. Most show exhaust systems are made of highly polished stainless steel or titanium.
	MUFFLER Mufflers are chambers that use various principles of acoustics to reduce exhaust noise from a deafening roar to more tolerable levels. The noise-reduction characteristics of a particular muffler depend largely on its design. Stock mufflers use closed designs with several internal baffles to deaden the sound. While this approach works well from an acoustic standpoint, it causes considerable backpressure and tends to degrade performance. Most aftermarket mufflers for sport compact vehicles use a straight-through design without internal baffles or chambers. Instead, they channel the exhaust flow through a perforated pipe surrounded by a sound-absorbing material, such as fiberglass. Aftermarket mufflers are often tuned to provide a more aggressive, yet pleasing sound than stock mufflers. When shopping for a muffler, you'll notice that some are designed for display at the rear of the vehicle, while other "universal" mufflers are designed to be hidden under the car. The type you use is up to you, but be sure that your new exhaust system will fit properly underneath your car and that your exhaust tip will fit into any exhaust cut-outs on your rear bumper.
	EXHAUST TIPS If you opt to go with a universal muffler, you'll also need some exhaust tips to round out your exhaust. Size and style are entirely a matter of taste, but be aware that some high-end exhaust tips-besides looking better-incorporate removable silencers that can change the sound of your exhaust from a soft purr to a loud roar in an instant. These schizophrenic tips are great for enthusiasts who want the performance of a free-flowing exhaust at the track but don't like to attract the attention of the local constabulary while on the street. If you're simply looking to dress up your car's rear end, tips can also be used with stock mufflers to add some style at very low cost.

If you have questions about any of the above components, or if you're looking for the best custom exhaust package for your vehicle, give the SCO Tuner Pros™ a call at 800-622-9541. They'll help you choose from the thousands of options available to you at the MotorWeb Store.