Switching the original, factory-fitted exhaust system for a high-performance exhaust can result in some significant gains in terms of horsepower, which is obviously of great benefit to lovers of speed and power; but there are a number of other reasons why you might want to upgrade – and plenty of questions around why, and how, too.
Over the years we’ve helped thousands of car owners to upgrade their standard OE exhausts to performance exhausts and along the way we’ve been asked a lot of questions. These range from the best brands when it comes to performance exhausts, what the overall benefits of the upgrade are and why people make the upgrade in the first place.
Here we’ve set out to answer some of the most common questions surrounding the wonderful world of sports exhausts to help you understand the true performance benefits.
We also think it’s worth taking a moment to explain all the different types of product on offer, because if you’re new to tuning the terminology can be a little confusing. So, without further ado…
What is a performance exhaust and why do I want one?
Put in the simplest possible terms, a performance exhaust system replaces some or all your car’s original exhaust system with improved pipework, silencers, and the like.
As with most things in life, your cars original exhaust will have been a bit of a compromise. Government standards and customer expectations for how quiet cars should be are increasingly strict, so it’s probably going to have been designed to favour quietness over performance and fun.
It will also have been designed for the original power output of the engine. It’s probably perfectly adequate for that power level, but once you start tuning the car it can become a limitation.
This means there’s two big areas for improvement for performance exhaust makers – sound and performance.
Sound
The sound is one of the biggest pull factors for some owners. A performance exhaust can transform the sound of a car. The combination of pipework and silencers mean each manufacturer can achieve their own trademark sound. While you probably notice the very loud aftermarket exhausts more, there’s actually a whole range of sounds on offer, depending on who’s exhaust you are fitting to your car.
This can range from the very boisterous through to a refined performance car sound. Most manufacturers will have a consistent quality to their sound.
You may also have a choice of different sounding exhausts from the same manufacturer. Many of them will offer similar exhausts with and without resonators (a silencer designed to cut out certain frequencies of sound) or silencers.
We’ll cover some of the top brands we do and how they like their exhausts to sound later.
Performance
A better flowing exhaust can help your car to generate more BHP. How quickly you can get the exhaust gasses out of the engine places a limit on how quickly you can get fresh air into the engine and thus how much power can be made. A better flowing exhaust always improves the power your engine can make. Performance exhausts achieve this in several ways. Pipework diameter, exhaust layout, and reducing obstructions in the exhaust all play their part.
On a non-turbo engine, it’s all about keeping the gas in the exhaust flowing quickly. The action of getting the exhaust gas out of the engine helps it draw in fresh air at certain parts of the rev range. The quicker everything is flowing, the more benefit you get from this. On a turbo-car, the big priority is increasing the flow-rate of the exhaust. The more gas the turbo can get out, the more efficiently it can force feed your engine with air at the other end.
While you will probably get some benefit from replacing any part of the exhaust system with performance parts, the benefits are most pronounced when you’re replacing the most restrictive parts of the original exhaust – which tends to be the catalytic converter and downpipe. When fitted alongside the correct software, you can get some serious power gains when you replace the original catalytic converter.
