Improving Exhaust Flow: Challenger Cat-Backs

A cat-back exhaust system is an exhaust system that extends from the catalytic converter(s) to the tip of the exhaust system. It typically contains a mid-pipe, muffler(s), tailpipe(s), tip(s), and the clamps, hangers, and fasteners needed to install the system.

Aftermarket cat-back systems typically contain tubing that is larger in diameter than the stock exhaust system. It allows for more flow through the exhaust system and better sound quality.

The mid-pipe is the pipe that connects between the catalytic converter(s) and the muffler(s). The tailpipe(s) fasten to the exit of the muffler(s) and extend to the edge(s) of the vehicle. The tip is the decorative piece that bolts or welds onto the end of the tailpipe(s). The tip(s) are the shiny piece(s) at the very end of the exhaust system that can be seen from outside the vehicle.

If you are adding a cat-back exhaust system to a stock engine, the power increase will be minimal. The main benefit of a cat-back exhaust, on a stock engine, is sound. Almost any cat-back system will sound much better than a stock exhaust system. If you are adding a cat-back exhaust system to an already modified engine, that is where you will see the most performance benefit.

The piping diameter is almost always larger than stock. This allows the exhaust gases to escape faster, creating better flow through the system. With other modifications to the engine, such as a cold air intake, intake manifold machine work, or cylinder head machine work, the engine can breathe more efficiently.

The aforementioned work, along with a larger exhaust diameter, allows air to flow through the engine better. You can then add more fuel and create more horsepower. Even if you add a cat-back system first, you can do this engine work afterward and still reap the benefits.

Another benefit of the cat-back exhaust system is that they usually follow a similar route to the factory exhaust system. They utilize the factory exhaust hangers and fall under the factory heat shields. This means little to no alterations to the vehicle. Because the system bolts in after the catalytic converters, the factory emissions equipment remains intact. That is especially important in states where an annual emissions inspection is required.

Cat-back exhaust systems are usually made of two different materials: aluminized steel and stainless steel. Aluminized steel is basically the same material that the stock exhaust system is made of.

They are designed to have a similar life span as the stock exhaust. The aluminized system will look similar in appearance to the stock system, but with a larger pipe diameter and a different looking muffler.

Stainless steel systems are of a much higher quality. They are constructed to last a lot longer than a stock or aluminized system. They are almost impervious to rust. These systems come with a longer warranty.

Many stainless steel exhaust systems are also polished to add a little bling to the underside of your vehicle. They will have an almost mirrored finish. A stainless steel system should keep your ride sounding and performing well for many years to come.

A cat-back system can be used in conjunction with a header as long as the header is meant to bolt up to the factory catalytic converter. If the header does not bolt up to the factory catalytic converter, a custom adapter pipe can be made by a qualified exhaust shop to connect the two.

While this retains the Challenger’s factory converter, you will only see a partial gain in horsepower with this setup. To obtain the full performance gain, it is recommended to replace the factory converter with a high flow unit. A high flow converter will keep things emissions legal, but will allow more flow.

When discussing aftermarket performance mufflers, there are three types. The explanations below will help you choose which one is best for your Challenger:

Glasspack: A glasspack muffler is a straight-through, single tube design. There is a single tube inside the muffler, with perforations punched into the inside. The tube is surrounded on the outside with fiberglass mat packing. The outer shell wraps around the outside of the fiberglass packing. This design allows exhaust gases to flow straight through and out of the muffler.

Some of the sound penetrates the perforations and is absorbed by the fiberglass packing. Glasspack mufflers emit a very loud, high-pitched sound. They are typically the loudest type of street muffler.

Chambered: The chambered muffler is constructed with anywhere from 1 and 4 chambers on the inside of the outer shell. The exhaust enters the center chamber(s), and encounters baffle(s) on the inside.

The exhaust gases quickly flow through and out of the muffler while a portion of the sound waves are impeded by the baffles. Chambered mufflers are known for their deep, metallic tone. They are middle of the road as far as sound volume goes.

Turbo: The turbo muffler is constructed in a similar manner to a stock muffler. There is a metal outer shell, with 2 or 3 perforated tubes inside.

Unlike the S-shaped path of the stock muffler, the turbo muffler has a more circular flow path. Exhaust enters the muffler and gases escape through the perforations in the inner tubes. Sound is partially restricted by the tubes. This is easily the quietest design of aftermarket mufflers.