July 17, 2017
Thinking of Buying a New Exhaust? – Commentary
Knowing what to look for will help manage your expectations.
What does my exhaust system do?
As your pistons move up and down, your valves open and close according to the timing of your cam shaft. Just as the spark plug fires and the piston is driven to the bottom of its stroke, your exhaust valves open, allowing any unburned gaseous molecules to be pushed out of the cylinder. This is how all exhaust systems work regardless of manufacturer quality or price.
How does an exhaust system affect performance?
If unburned gases have trouble exiting your cylinder, your engine is losing power because it has to expend energy driving the gas out. A performance exhaust is designed to create an environment where gases are flowing freely and at high velocity out of the cylinder with minimal effort from the piston.
The velocity of gases escaping your engine is a science and is the reason there are so many exhaust systems available. It’s also why results vary so much from product to product, bike to bike. Your riding style, throttle management, and even whether you ride in mud, or on the trails, will affect the amount of performance you benefit from with an aftermarket exhaust.
Most aftermarket exhaust systems will give you less than a 5 horsepower gain without a tuner, around 8-10 horsepower gain with a tuner, and as much as 11-12 with exhaust, high-flow air filter, and the proper fuel management program for them.
Why does sound change based on the exhaust I choose?
To reduce the restrictions on gases flowing from the engine exhaust manufacturers rely on different designs, materials, and packing. As these designs change and change the velocity of the gases escaping, the sound of the fuel exploding in the cylinder reverberates through the exhaust in different ways, creating different sounds.
Some manufacturers specifically manufacture exhausts to reduce the noise that the engine produces. This is most common with hunters who need their bikes to get quietly to and from their hunting grounds without disturbing wildlife.
Do I Need a Fuel Tuner?
The short and annoying answer is “probably”. The fuel management system in your machine is designed to work very specifically with the amount (density and velocity) of air the stock air intake system permits, the amount of burn that can be expected by the stock spark plug, and the amount of backpressure generated by your exhaust system. Changing any of these things will have varying impacts on your fuel mapping. However, if you make a change that doesn’t adversely different than the stock setup, and your new exhaust is primarily there to change the engine sound, you may be able to run without the fuel tuner, but you will get more benefit from any exhaust if you add a tuner.
Most fuel tuners assume you have changed to a high-flow air filter, so you’ll get maximum benefit from your new exhaust and fuel tuner if you also increase air flow into the engine as well. Some manufacturers even package a high-flow air filter they feel will best complement the exhaust and their fuel mapping to help you gain maximum performance.
Should I Buy a New Exhaust?
I would suggest that if you’re in a position to purchase the exhaust and the tuner AND you’ve done the research to know which exhaust matches your particular setup and riding style, you shouldn’t hesitate. Or, if you’re just trying to quiet your machine so you can sneak out to your tree stand or duck blind, definitely feel free to make the investment.
But, if you can’t make the investment in the tuner and the exhaust, or you don’t know if the exhaust is set up for those big tires and the new clutch kit you’ve installed, I would hold off. An informed decision is definitely going to be important – ask lots of questions and trust no single source for information.
Who Makes the Best Exhaust?
There’s no short answer because every exhaust is different for every machine, and every machine is different (lifts, tires, axles angles, etc.), and every rider is different (weight, throttle control, riding environment, etc.).
Here is a list of aftermarket exhaust manufacturers:
GSE Performance – gseperformance.com
EZ Ryde – ezryde.com
Alba Racing – teamalbaracing.com
HMF Racing – hmfracing.com
FMF Racing – fmfracing.com
Big Gun Exhaust – biggunexhaust.com
Pro Circuit – procircuit.com
Yoshimura – yoshimura-rd.com
Two Brothers Racing – twobros.com
MBRP Racing – mbrpatv.com
Quad Boss – quadboss.com
Kolpin – kolpin.com
Gibson Performance – gibsonperformance.com
Trinity Racing – trinityracing.com
The Silent Rider – ATV Silencer.com
Buying a new exhaust is a fun time. There are few modifications you’ll make that will get people talking more than the sound of your new exhaust. Take your time and don’t jump into your purchase and a new exhaust, tuner, and air filter will be one of the best power upgrades you can make to your machine.
Please feel free to comment below to let me and our readers know about your experiences (good and bad) and about any good, knowledgeable technicians you’ve come across. They can be hard to find and invaluable when trying to find the right setup.