The most common first or second modification for the Ford Mustang is Exhaust. Be it just a muffler, axle-back kit, cat-back kit, midpipe, or even headers, Mustang enthusiasts want the true American muscle sound and performance achieved by upgrading the exhaust components on their rides.
Not only will you get a louder tone by swapping the muffler(s) or installing hi-flow catalytic converters, you will also get more power and better fuel economy. Since most aftermarket applications use free-flowing, mandrel-bent pipes that flow better than stock pipes, the exhaust gases will be extracted from the heads more effectively. This extraction of gases allows for more air and fuel to be brought into the engine for combustion, and more power is the result.
A common reason many new Ford Mustangs go unmodified is the fear of warranty nullification. In fact, the warranty of your exhaust components will be voided if you alter or replace them, but most manufacturers have defaults in workmanship warranties on their products. If you buy your components new, you should have no fears of warranty nullification.
From the factory, V6 Mustangs have a different exhaust setup than the V8 Mustangs. The V6 Mustangs have short tube, cast iron headers for each head, 2 catalytic converters per bank, 2 oxygen sensors per bank, a Y-pipe that joins the 2 sides into one, and a single tail pipe. The V8 Mustangs have short tube, cast iron headers for each head, 2 catalytic converters per bank, 2 oxygen sensors per bank, an H-pipe that maintains a dual exhaust, and dual tail pipes. The difference is noted in this illustration:
There are many options to upgrading the exhaust components of your Ford Mustang. Headers, midpipe, and cat-backs make up the exhaust sytem, and each can be upgraded for better sound and more power.
The piping is a key element to the exhaust system. The diameter of pipe is determined by the power your engine is making, and mandrel bent pipes are more costly but flow better than crush bends that many muffler shops commonly use. A quality mandrel bent 2.5″ pipe can flow up to 35% better than serrated or crush bends around curves in the exhaust system. This better flow equates to more power. Also, stainless steel pipes will not rust and will hold up longer than aluminum pipes. A ceramic coating is often used on headers to keep the heat inside and protect the pipes from rust as well.
The muffler is another key element to the exhaust system. Most people buy a certain cat-back because of then included muffler and the sound they wish to achieve. Chambered muffler and straight-through muffler designs are available, and depending on the application, one may sound better and perform better than the other.
Long tube, mid length, and short tube headers are available for the Ford Mustangs. From the factory, the Mustang comes with restrictive cast-iron short tube headers, but a lighter-weight, better-flowing short tube can be used for a little gain. The reason most enthusiasts upgrade to a short tube header is to remain emissions legal. Also, a short tube header bolts right up the the existing mid pipe, so this modification can be done to a stock vehicle without changing anything else, or if a new mid pipe is wanted, a stock length mid pipe is needed.
Long tube headers are the best option for high-powered, naturally-aspirated engines or superchared and nitrous-injected engines. Long tubes allow for the best flow of any design, but are often not street legal in emissions counties. With long tube headers, an obdII car needs oxygen sensor extenders for the front oxygen sensors that measure air/fuel ratio and MIL (malfunciton indicator lamp) eliminators for the rear oxygen sensors to keep the car functioning properly.
Mid length headers are just that; mid length. They are longer than short tubes but shorter than long tubes, and many flow very well and maintain a use for a catted midpipe. If you need catalytic converters for a lenient emissions county, you can get by with mid length headers and high flow catalytic converters.
There are four types of mid pipes in three sizes. The three sizes depend on the headers being used. For stock or short tube headers, a long mid pipe is needed. For mid length headers, a mid length mid pipe is needed. For long tube headers, a short mid pipe is needed.
The four types of mid pipes are a Y-pipe, an H-pipe, X-pipe, and true dual pipes. The Y-pipe has a Y-shaped crossover between the left and right exhuast banks that joins them into one pipe for exiting. This design is cheap to manufacture but very restrictive to exhaust flow. All 4-cylinder and V6 Mustangs have this midpipe.
The H-pipe has an H-shaped crossover between the left and right exhaust banks that equals out the exhaust gases on each side and allows for a dual flowing exhaust. An H-pipe will give you a low tone, and the H-pipe sounds best with a chambered muffler.
The X-pipe has an X-shaped crossover between the left and right exhaust banks that equals out the exhaust gases on each side and allows for a dual flowing exhaust. An X-pipe will flow better than an H-pipe, but give a more raspy tone. The X-pipe sounds best with a straight-through muffler.
The true dual design has no crossover pipe to equal out exhuast gases from the left and right bank. Most true dual setups are fabricated and cheap to make. They do not flow better than H or X-pipes, but they do flow better than Y-pipes.
A midpipe can also be labeled street or off-road. A street use midpipe has atleast one pair of catalytic converters to remain street legal in emissions counties and to remain legal to be sold in the United States. High flow catalytic converters do cut down on exhaust emissions, but they are restrictive to the removal of exhaust gases. An off-road mid pipe contains no catalytic converters, is cheaper to manufacture and sell, makes more power than street midpipes, but is not street-legal in emissions counties.
Cat Back systems are usually purchased by brand loyalty due to the sound of the included mufflers. There are many reputable brands that make either a straight through or a chambered muffler and they all univerally bolt up to midpipes. All catbacks will flow within 3-5 rwhp of each other with Magnaflow making the most power. Since the companies are so close in power, buy based on the sound you prefer.
Quality exhuast components will bolt on easily, and can be installed with common hand tools in the driveway in a few hours. Wake up your Ford Mustang with an off-road exhaust that will sound as mean as the power it makes!