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Facts and Functions of an Aftermarket Exhaust

A lot of people preach installing an exhaust system, citing such benefits as improved sound and performance as the reason why this should be done. What nobody ever really talks about, though, is what–exactly–installing that exhaust does for your vehicle. The thing is, sometimes it’s not enough to know that something does good, but more specifically, to know exactly what good it does and how it does this.

The Legality

The first thing to consider is, of course, whether or not you can install an exhaust on your vehicle. This is not meant to be a determinate of whether or not your car will accept an exhaust (as all cars will!) but instead to consider the legalities of the exhaust. With Cat-Back and Axle-Back exhausts, this isn’t really an issue, of course. These exhausts install from the catalytic converters–and, consequently, the second O2 sensor–and back. This is nearly always 50-State legal–a distinction that California has made difficult with their CARB (California Air Resources Board) requirements. The same can not always be said about Headers, or any other form of exhaust system that changes out the Cats, or Catalytic Converters (which functions to reduce the toxicity of emissions gases from vehicles). For this reason, somebody should always do thorough research about the legalities of Headers before installing them on their vehicles.

Beyond the legalities of the emissions themselves, some states have noise regulations in place in regards to vehicle exhausts. Now, it’s hard to find a system loud enough to upset these noise regulations, but it’s still worth checking before making a purchase and doing an install.

If you are concerned with the legality of a system, the ultimate solution is to stick with a Cat-Back exhaust from a major company. Borla, Corsa, MagnaFlow and others pride themselves in offering 50-state legal exhaust systems for a number of different vehicles (even though MagnaFlow does have a line of exhausts that do not meet 50-state requirements, so be safe with those). Sticking with a Cat-Back system provides the most performance bang for your buck and the greatest guarantee of legality at the same time. In fact, the benefits of a cat-back system are so numerous (vehicle engine efficiency, improved exhaust tone, improved exhaust volume, legal, HP and Torque gains, etc.) that the Cat-Back Exhaust has become considered the unquestionable number 1, first most important performance modification piece.

How It Works

An exhaust functions as a long funnel with the purpose of combustion waste-gas expulsion. All combustion engines create toxic fumes from their combustion process, and the exhausts collect these gases from the engine manifolds and send them down through a series of snake-like expulsion tubes, through the vehicle’s catalytic converters for toxicity reduction, and out the tail-pipes. The catalytic-converter performs its toxicity reduction through the use of a two-part filtration system, which utilizes platinum and rhodium in the first half reduction catalyst to reduce NOx emissions, and a burning off of Monoxides Hydrocarbons in the second half. The result is more than  90% of all toxic vehicle emissions being destroyed. The importance of this piece should signify why it’s a slippery slope, legally, to change it out.

How then, if the expulsion of toxicity is the function of an exhaust, can an aftermarket exhaust provide benefits of performance and tone? It seems strange, but, it’s ultimately very simple. Aftermarket exhausts specialize in offering more efficient means of this emission flow. What this means then is that the engine may expel more waste more quickly, and, as result, breathe more easily. By doing this, too, it allows for a more efficient air intake from the vehicle. What this means, then, is that the engine has to work less hard to performance a necessary function, and as result, is able to produce extra power. By doing this, as well, the exhaust will offer a more aggressive and powerful tone, with a higher exhaust volume, as the extra air flow will resonate more through the exhaust pipes and chambers, and the increased performance will simply have your engine sounding better.

To Cat-Back, or Not to Cat-Back?

When it comes to performance vehicle exhausts, you are presented with a lot of options. From manufacturer (it’s a long long list that includes names like Borla, Corsa, Magnaflow, Akrapovic, Billy Boat, and more) the list of options only gets longer. Each manufacturer offers various different styles of exhausts, from their most reserved Touring and Street models, all the way to the loudest options, which are often times given catchy names like XTreme, ATAK, and Competition. The best way to decide between manufacturer and manufacturer models really comes down to personal preference. Some companies are reviewed more highly than others (most mechanics I know swear by Borla Exhausts), but they all offer very similar benefits when it comes to performance and build, so it comes down to the exhaust tone and volume you want. Now, sadly, unless you’ve got a whole lot of automobile crazy friends, you wont be able to hear each and every system in person. The internet offers a brilliant solution to this, though, in the form of YouTube. YouTube offers a means by which you can see and hear nearly every exhaust ever manufactured on each and every vehicle available, which makes it an indispensable tool for the exhaust shopper.

Ok, so, you’ve decided on manufacturer and exhaust model, the last choice comes down to a simple one: Cat-Back or Axle-Back? A lot of people choose Axle-Back exhausts because of the price difference, but, if you can afford Cat-Back, an Axle-Back is a mistake. For a little bit more, a Cat-Back offers much increased performance gains, and a much improved exhaust tone and volume. Often times, with the less aggressive exhaust options, there’s no real discernible difference in sound between a stock exhaust and an Axle-Back offering, and, we all know that the biggest and most enjoyable aspect of an exhaust is the enhanced ability it offers to hear your car while driving it. Also, the HP and Torque gains between a Cat-Back and an Axle-Back are almost 100%, with the average Cat-Back offering 14-25 HP, and the Axle-Back offering 8-14HP, or so.

What’s the actual difference between the two, though? Cat-Backs include all aspects of the Axle-Back (mufflers, and tips, typically, the very rear section of the exhaust) and include extended piping. The extended piping is more wide open and more efficient, and many times includes a mid-pipe option like an X-Pipe or an H-Pipe, which evens out the exhaust tone for a more clean and aggressive crescendo across the RPM range. By adding on these exhaust section pieces, a Cat-Back provides a much more powerful exhaust tone.

Other Improvements?

On top of the benefits listed above, a new exhaust also offers improved build quality over the stock. This quality comes as result of companies specializing their efforts in to exhaust R&D, as opposed to the stock exhausts which are more of an after-thought than anything else, typically. Aftermarket performance exhausts are often times made with higher quality materials, as well. Aircraft grade stainless steel tends to be the industry standard, but some exhausts are built with full titanium construction, also. These materials are stronger and more durable than stock, lighter, and tend to be more visually attractive, also. All of these aspects provide a product for your vehicle that will help to reduce its weight and make it more visually appealing.

Installing an Exhaust

Exhausts are not the most difficult install in the world, surprisingly. Cat-Back exhausts tend to be direct bolt-on replacements, and can be performed by an individual with minimal experience if they have access to the right tools. Those tools are, though, solid jacks/a lift, the proper wrenches (an air-powered wrench works wonders), and a steel resolve. The system can be removed and put on in pieces, which makes it simple, but is still a rather time-consuming process, and can take 2-3 hours. If you have the determination to do it yourself, though, by all means go for it. A number of videos exist on the internet that detail how to install an exhaust, and a talented or experienced installer can switch an exhaust out in about an hour’s time.

All that being said, if you feel uncomfortable with this as a DIY job, any competent mechanic can install an exhaust for you with relative ease. If they ever try to charge for more than 3 hours, also, it’s worth giving them an argument, as the work definitely will not take that long (unless they’re actively dyno-ing and tuning the system, of course). Thus, the issue of tuning comes in to play, and this is one of the questions most often asked. Do you need a tune with an exhaust?

The short answer to that is: no. The long answer to that, though, is: no, but it couldn’t hurt. Anytime you modify your vehicle, especially an aspect that changes the air flow through the engine system, you’re asking the engine to perform differently that it did at stock. An Exhaust, by itself, should never ever throw a code when changed out, but when installed in conjunction with other modification pieces (i.e. intake, headers, etc.) a tun is very very useful to ensure that your vehicle is running as properly and efficiently as it can.

So, ultimately,

I hope that this helped you understand your exhaust system better. Also, I hope it helped you make the decision to begin your vehicle tuning and performance modifications with a new exhaust. Few components are as important or as useful, and even fewer will provide you with the HP Bang for the Buck that an exhaust will. Once an exhaust is installed, too, every new modification piece you install will help get both more HP from the new enhancement, as well as from the exhaust itself. Now, the last thing to do, is to figure out which exhaust is right for your vehicle. My vote goes to Borla (mostly b/c of their price to quality ratio, and their general availability), but, there are always other, very viable options from a variety of different manufacturers.