If you’re like most retro or custom riders, at the top of your parts list is an aftermarket motorcycle exhaust. With strict Euro-5 emission regulations, factory-fitted silencers can sound somewhat lacklustre.
But beyond sound, are there any benefits to upgrading your exhaust? In short, yes. In this article, I’ll discuss some of the benefits of an aftermarket exhaust.
Key Takeaways
- Upgrading your exhaust will enhance your motorcycle’s sound.
- Aftermarket units invariably reduce weight and improve airflow, leading to performance gains.
- You expect performance gains from ~1 to 15% – depending on whether you fit slip-ons or full-system
- Aftermarket exhausts transform your bike’s aesthetic to match your style.
Primary Function of A Motorcycle Exhaust – Removal of Waste Gases
The distinctive-looking motorcycle exhaust’s primary function is to collect and expel waste gases produced during the combustion phase (of the engine cycle) as efficiently as possible. Stock exhausts are also built to reduce noise and carbon emissions.
Two Types of Aftermarket Exhaust to Install: Slip-on or Full System
There are two types of aftermarket exhaust that you may be considering: slip-on or full-system.
Aftermarket Motorcycle Exhausts – Slip-On vs Full System
- Slip-On Exhaust: This is attached to the pipes, replacing the stock silencers/end cans or mufflers, if you prefer. They’re relatively straightforward to install with minimal tools, making it a job that even novice tinkerers can easily complete. ~1-3% performance gain (mainly weight reduction and sound improvement)
- Full-System Exhaust: Depending on the bike, installing a full-system exhaust can be a finicky, protracted affair. It requires the replacement of the headers, pipes and mufflers. (~5 – 15% performance gain, depending on the bike, setup and tuning)
Prices range from around £80/$100 for end-cans to ~£3,200/$4,000 for off-the-shelf full systems. You could also opt for a custom-built exhaust, which could be somewhere in between those costs or even more depending on its materials, engineering and craftmanship.
Should you opt for Professional Installation or DIY?
Choosing between professional installation or doing it yourself entirely depends on your technical skills and confidence and whether you’re going for slip-ons, an off-the-shelf full system replacement or a custom-built system.
Most of the shelf aftermarket pipes use mounting points that align with the OEM manufacturers’ positioning. So, with some technical competency, the right tools and a free morning or day, you can do it yourself.
However, if you’re unsure, it’s always best to rope in a competent mate or hire a professional, especially for full system replacements. Needless to say, custom-built systems will require professional installation.
Why Fit an Aftermarket Motorcycle Exhaust – Benefits of Upgrading
There are three main benefits to purchasing aftermarket pipes – whether a full-system or slip-on end-cans – either custom or off the shelf: Sound, aesthetics and performance.
1. Improved Sound
Aftermarket pipes will alter the sound of your motorcycle, making riding the bike a more visceral experience. Typically, they’re louder (but not always) and often produce a deeper, more pleasing exhaust note.
The material and design of the exhaust directly affect the sound quality. For instance, stainless steel tends to create a sharper sound, whereas titanium may deliver a warmer tone.
Stock exhausts, on the other hand, are designed to minimise noise emissions – therefore, they can be somewhat muted and high-pitched. Although, to be fair, the Triumph and Royal Enfield twins sound fairly good straight from the sales lot.
2. Aesthetics: Visual Appeal
A handpicked aftermarket or custom-built exhaust can alter the look of your motorcycle dramatically. Various styles and finishes allow you to tweak your bike’s aesthetics – by cleaning up the rear end or giving it a hyper-aggressive look.
If you ride a retro motorcycle, whether it’s a cafe racer, roadster, scrambler, bobber, custom or something in between, you’ll have no problem finding a non-OEM unit to fit the style of your bike.
Several manufacturers, such as British Customs, Zard, Hitchcox, Tech Bike Parts and many more, produce full systems or slip-ons for modern classic motorcycles.
Among their product ranges, you’ll find options composed of various materials, including stainless steel and titanium – sometimes, combined with carbon. There are many designs and styles, offering a variety of mounting positions. Many are built exclusively for specific modern classic models.
3. Enhanced Performance: 1 to 15% increase
The third, and for some, the most important reason to upgrade your stock exhaust is performance. Swapping your stock exhaust for an aftermarket unit can improve the performance of your bike through weight reduction and improved airflow.
Perhaps, it was the case, some time ago, that stock exhausts were poorly tuned there for the gains were greater. Nowadays, however, stock exhausts are well-tuned by manufacturers and allow the bike to perform to its full (stock-state) potential. Nonetheless, that’s not to say you can’t eke out performance gains by combining the right exhaust.
When installed, you’ll find that the engine runs cooler and you’ll probably need an ECU remap. However, for some bikes, like the Thruxton R and Bonneville range, you merely need to leave the bike idling until the fan kicks in. At that point, the ECU will automatically recalibrate itself.
You can expect somewhere in the region of 1% performance improvement for installing slip-ons up to 15% for a full system, race-engineered or custom-built pipes. Replacing the catalytic converter with an x-pipe can offer performance gains at the top end of that range.
Improved Performance Through Weight Reduction
Many stock exhaust systems are heavy and contribute significantly to your motorcycle’s overall weight. Aftermarket units tend to be lightweight, therefore reducing the overall weight of your bike. That means a better power-to-weight ratio offering improved acceleration, agility, handling and braking.
Improved Performance through Better Airflow and Reduced Backpressure
Stock exhaust systems are designed with restrictions, such as chunky baffles and catalytic converters, to meet waste emissions and noise regulations. This can create backpressure, forcing the engine to work harder to expel gases.
Aftermarket exhausts, slip-on and full systems (whether of the shelf or custom) with wider-diameter pipes and high-flow designs reduce this resistance. This allows exhaust gases to escape more efficiently, meaning an improved scavenging effect (drawing in fresh air-fuel mixture).
This, in turn, optimises combustion and unlocks additional horsepower and torque. more responsive throttle, making your bike feel faster.
Final Thoughts on the Benefits of Aftermarket Exhaust
Ultimately, an aftermarket exhaust is less about pure performance and more about transforming your bike’s character. You’ll get a deeper growl and turn a few heads. But performance gains are more of a bonus than a guarantee.
Slip-ons offer a slight improvement, primarily through weight reduction. However, full systems can unlock significant power – if you’re willing to invest.
For most riders, a slip-on might be just what you need to personalise the look and sound of your bike. Performance tinkerers, however, should lean towards full systems and ECU tuning for those extra horses.
Whatever route you take, an aftermarket exhaust is your way to make your bike truly yours.
