On a classic car, all the exhaust had to do was evacuate gases from the engine, transporting them to the rear of the car to prevent the driver and passengers from breathing in the fumes. That was it.

How times have changed. Nowadays, exhaust systems not only play a crucial role in shaping a car’s power output (and even the way power and torque are delivered throughout the rev range), they have to help ensure the vehicle meets emissions and drive-by noise regulations, both of which have become significantly stricter since the early 1990s.

That’s a lot of different tasks for one component to handle, which is what makes the idea of a performance exhaust system so alluring. Free from the legislative requirements OEMs have to stick to, aftermarket exhausts focus largely on performance and enhancing the sound of your car, rather than suppressing it.

The average motorist might prefer a quiet exhaust and might not notice the additional power a performance exhaust can deliver. But if you love driving and want to make every journey more exciting, a new exhaust will probably be pretty high on your shopping list.

In this guide, we’re going to help you work out whether or not an upgraded exhaust system is right for you. Below, we’ll cover the benefits and potential pitfalls of installing one, telling you everything you need to know before you buy. We’ll even take a closer look at the different sections of an exhaust system, explaining the impact of upgrading each component on performance, sound and emissions.

The benefits of aftermarket exhaust systems

So, why does anyone bother ditching their car’s standard exhaust system in favour of an aftermarket one? Several reasons…

Increased power and torque

For many, this is the main selling point of an aftermarket exhaust system. On a lot of cars, the standard system effectively ‘chokes’ the engine, restricting its ability to extract exhaust gases and hampering the efficiency of the combustion cycle. If the engine can’t breathe in and out efficiently, it’s not going to achieve its true potential on the dyno.

Manufacturers fit restrictive exhaust systems to cars for a variety of reasons. It could be that they have to do it in order to meet noise requirements or the latest European emission standards. Sometimes, they even fit deliberately restrictive systems to cheaper models in the range, preventing them from producing as much power as their more expensive sibling. You’d be surprised how often things like this happen!

Typically, performance exhaust systems have a larger internal diameter than stock ones, allowing exhaust gases to flow through them more efficiently. They might also feature straight-through mufflers instead of baffled ones, which further helps to eliminate restrictions and speed up the flow of exhaust gases. Reducing backpressure not only enables the engine to produce more peak power, it can help turbochargers spool up more quickly, reducing lag for a more lively, responsive driving experience.

Combine your performance exhaust with a quality induction kit and your engine will be able to breathe in and out more efficiently, boosting power further.

A more exciting sound

Lots of people fit aftermarket exhausts for this reason alone, and we can’t say we blame them. Although plenty of older vehicles sounded relatively dramatic straight out of the factory, the same can’t be said of many newer vehicles. Although there are some notable exceptions (the V8 Jaguar F-Type and the naturally-aspirated C63 AMG come to mind), most cars from the 2010s onwards tend to sound quite muted in their stock form. Plenty of ‘80s and ‘90s cars fall into this category too.

Ditching your stock exhaust for an aftermarket one can dramatically change the way your car sounds, all while enhancing performance and maintaining its legality come MOT time.

Reduced weight 

Thanks to their reduced complexity (and the use of lightweight materials in many cases), aftermarket systems are usually a fair bit lighter than their stock counterparts - another bonus for those in search of ultimate performance.

Shedding weight is always beneficial from a performance standpoint, not just in a straight line but through corners and under braking. A lighter car will stop better and corner quicker than a heavier one, making an aftermarket exhaust a no-brainer for serious enthusiasts.

Improved quality and longevity

This one may come as a surprise, but it’s true. Many stock exhaust systems are designed to be as cheap as possible to manufacture, and they’re often made using mild steel, which doesn’t last that long on British roads before corrosion begins to take hold.

Aftermarket systems are usually made from either stainless steel or titanium, both of which are significantly more resistant to corrosion than mild steel. That means once you install a quality aftermarket system, you probably won’t need to replace it for a very long time - much longer than if you fitted another standard mild steel system.

Better-looking exhaust tips

The final point in favour of aftermarket exhausts is the way they look. It might seem like a small detail to the average motorist, but an enthusiast can spot a modified exhaust in an instant. A larger, more prominent exhaust tip gives your car a little added aggression before you even start it up, which is an added bonus.

Are there any downsides to an exhaust upgrade?

Depending on your point of view, yes. As much as we love upgraded exhausts, there are plenty of potential downsides and pitfalls to keep in mind before you rip off your standard system…

• You can easily make your car too loud: You might think you want a loud exhaust, and you might enjoy it at first. But if you go too far and make it too loud, that initial feeling of excitement will soon morph into regret, particularly if it’s your daily driver. Having a louder exhaust is fun, especially on a weekend car – but if you make your daily commuter so loud that it drones on the motorway and sets car alarms off as you drive by, you’ll wish you hadn’t!
• It’s sometimes harder to pass your MOT: If you just install a cat-back system and don’t mess with any of the emissions control components, you won’t have to worry about this. But if you install a sports catalytic converter, for instance, you might find it tougher to pass the emissions test on your next MOT. Decat pipes are an absolute no-go come MOT time, unless your car is old enough not to require a cat.
• You’ll get more attention from the law: If you fit a louder exhaust to your car, you’re bound to attract the attention of the police as you drive by. Just make sure that your car is totally legal and MOT-compliant should you ever get pulled over.
• You could fall foul of track day noise limits: This ties in with the first point. Make your car too loud and there’s a risk you won’t even be allowed on track, as most tracks have strict noise limits in place.

How to upgrade your exhaust system

As you’ve probably gathered by now, upgrading your exhaust system is all about striking the right balance. It’s got to flow freely enough to enhance performance compared to the stock system, but you don’t want it to be so loud that you make enemies of your neighbours. You’ve got to make sure your car remains legal when your next MOT rolls around, too. So, how do you do that?

Choosing the right components

The first step is to choose the right components. If you’re just looking for a little more volume and a mild performance upgrade, a cat-back exhaust system is the simplest solution - especially because it won’t affect your car’s emissions output.

For the ultimate performance upgrade, opt for a complete system that runs from your manifold right the way back to the rear of the car. To maintain MOT compliance, you can either keep the standard catalytic converters installed or switch them out for sports cats, which are less restrictive than their factory-fit counterparts.

Selecting an installation specialist

Once you’ve selected the right system for your car, you’ll need a competent specialist to install it. As well as offering a wide range of quality aftermarket exhaust systems from brands like Armytrix, we offer installation services at our workshop in Cleckheaton, meaning we can both supply and fit your new exhaust on the spot.

To find out more, check out our complete range of exhaust systems today, or get in touch with our team of experts for advice - we’re always happy to help.