Just about everyone has come across a car with an exhaust that either sounded like a race car, sounded like a pissed off bee, or looked weird. You’ve seen tubes, chrome pipes, and even huge holes. The question is what is what and what should you buy? This guide’s purpose is to explain the common automotive aftermarket exhaust and pros and cons of each type of system. 

If you are reading this, you know that the purpose of the exhaust is to get rid of burnt gas that was used to propel the car. The only reason you would change the existing exhaust is for three reasons: The old one broke, performance, or looks (and sometimes a mix of all 3).

An entire exhaust system comes in 5 pieces (99.5% of the cars though there are some cars that has different setups). From the engine there are pipes leading from each cylinder and merging at the catalytic converter. Those are called exhaust down pipes/headers/exhaust manifold. Then there is the catalytic converter which converts the exhaust into something that isn’t quite so toxic to the environment. Next is the intermediate pipe which is the pipe that connects from the catalytic converter to the around the rear axel. This pipe also houses the resonator that helps to smooth out the exhaust sound. Then there is the muffler and finally the tail pipe

Header:

The first piece you can modify is the header. The goal of the header is to reduce back pressure and thus allowing the exhaust to not fight the engine trying to expel it. There are two main materials used. One is stainless steel and the other is ceramic coated steel. Stainless steel looks better and in general has a much longer lifespan. The problem is because it’s just metal, the exhaust loses temperature faster and thus the exhaust gases slow down which in turn creates backpressure. So you figured if that’s the case, ceramic coated would be better since the purpose of ceramic coating is to lock as much of the heat in the gas as possible. True, but most ceramic coated headers rust really quick. To have the best of both worlds, you ceramic coat your stainless steel header but that costs quite a bit of money. Then there is the design. In 4 cylinder applications, since each cylinder has it’s own pipe and they merge back together, it is either a 4-2-1 (four pipes into two pipes into one pipe) or a 4-1 (four pipes into 1). Generally speaking, a 4-2-1 produces most of it’s power in the midrange of the RPM (more usable) while the 4-1 at the high end (only when racing).

Catalytic Converter:

Next item you can change is the catalytic converter. Most catalytic converters are built to best react with the exhaust to clean it without robbing too much power. A more smooth design and sometimes a slight larger canister will help to expel the exhaust more like a pipe at the cost of the environment. These you can buy online as race catalytic converters. Some will actually use a what is commonly called a test pipe/straight pipe which is nothing more than removing the catalytic converter and replacing it with a pipe. This is highly illegal and comes with stiff penalties if caught.

Cat-Back:

Now comes the interesting part. The final pieces have the biggest range and potentially creates the biggest debate. You can replace the rest with what is called a cat back exhaust system. It replaces the exhaust system from the catalytic converter on back hence the term cat back. It normally comes in 2 or 3 pieces (2 for a single exhaust and 3 for dual exhausts). Reputable companies put these exhaust systems through rigorous testing and generally use higher quality materials and procedures. The pipes are thicker and coated to retain heat and smoothness and the bends in the exhaust are mandrel bent. Mandrel bending is nothing more than bending the pipe in a manner where the diameter of the pipe doesn’t change. This is significant because an exhaust is only as good as it’s weakest link and any change in diameter disturbs the flow. Also the welds won’t rust and the system has just enough flex to bend as the car does. Finally they should come with a resonator so that the exhaust has a nice low growl rather than a high whiny pissed off bee sound. $500-$1000 depending on the car and whether it’s dual exhaust or not.

Now the alternative is to build a cat back yourself. You can buy pipes that are mandrel bent from companies or your local exhaust shop can do it or just don’t bother. You can choose to skip the use of a resonator. The ONLY benefit of doing a custom job is because no manufacturer makes a cat back system for your car, you don’t like the styles, or you want to save money. There’s many drawbacks including welds that rusts, non-mandrel bends, thin pipes used and of course no testing of any kind. $250 - $600

Or you can do the next worst thing. Leave the intermediate pipe there and just replace the muffler and tail pipe. You can get some of the sound you want and the look with none of the performance. Much cheaper at $150 - $300.

Finally we have what I called RICE tips. Here you just weld on an exhaust tip. Nothing but looks and some sound (assuming you even cut the original tip off first).  $50?

 Remember size does matter. Having a pipe that is too large will also slow down the exhaust. If you remember your physics, pv=nrt. The trick is to find the proper size for your application.

Conclusion:

Personally if you are going to do it, do it right. Research because someone else has already done the setup and you can usually find pictures and audio clips of someone who did what you want to do. Top exhaust companies include: Greddy, HKS, DC Sports, Magnaflow, Borla, and Random Techology.

Zeoth

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