by D.Koopsammy

Created on: February 08, 2010

When we talk about an exhaust system, we generally refer to the piping that transfers the burnt fuel/air mixture out of the engine via the exhaust manifold. After market exhaust systems are sold as Turbo-back exhaust systems (vehicles equipped with a turbocharger), cat-back systems and Axel-back systems. Most after market exhaust systems serve to increase the flow of exhaust gases out of the engine which people refer to as allowing the engine to "breathe" better. This is achieved by using larger exhaust piping and a muffler that doesn't contain baffles, often termed as a non-restrictive exhaust system. Installing an after market exhaust system is one of the most prevalent modifications that is done to any vehicle since it provide both horsepower and torque gains depending on the engine which it is installed on and which exhaust system is chosen (whether a turbo-back or cat-back etc.).

Turbo-back systems are installed on vehicles equipped with a turbocharger and it serves to remove all the catalytic converters on the outlet of the turbocharger. I personally own a 2003 Subaru WRX which I installed a full Turbo-XS turbo-back system and was able to achieve 20 horsepower at the wheels and 25 foot-pounds of torque. This is quite impressive for just the installation of an after market exhaust system! Cat-back systems replace the piping after the catalytic converters (hence the name cat-back), this piping includes the muffler and piping leading up to the catalytic converters. Axel-back systems just include the muffler and a small piece of piping to the next available flange. Each system gives different horsepower and torque gains with the Turbo-back system giving the most, Cat-back systems second and Axel-back systems last. This is a general rule of thumb but it may differ depending on the type of vehicle!

Since after-market exhaust systems are less restrictive, they are louder than the stock exhaust system. Each after market  system has a decibel rating (unless it is custom made) so that you would know what noise level to expect. Once this level is below the maximum allowable level in your state, you should not have any problems from the cops. There are many after market exhaust system manufacturer for example HKS, Apexi, Turbo-XS, Borla, Greddy, Edge Racing etc. Each use different materials or specifications with respect to noise level and arrangement/fitment so when purchasing, you should have a look at all options. After market systems come in standard sizes such as 2.25 inches for non turbo vehicles and 3, 3.5, 4, 4.25 or 4.5 inches for turbocharged vehicles. Be sure to select the right size and noise rating for your exhaust because you don't want cop trouble and if the piping is too large you would experience a power loss instead of a power gain! If the piping is too large there wouldn't be sufficient backpressure on the exhaust valves so they won't work as efficiently and would cause you to feel a power loss, in other words a decrease in your acceleration rate at low rpms or maybe high rpms depending on the type of vehicle & engine. Hope this article helps you to understand more about after-market exhaust systems and proper selection! Cheers!

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