Exhaust Silencers On Performance & Mileage: Is It Bad?

By July 10, 2021Exhaust, Muffler

Exhaust silencers typically reduce the performance of your car by a little. Removing exhaust silencers through “muffler delete” can gain you 5-10 horsepower. 

As for gas mileage, exhaust silencers do not impact gas mileage enough for it to be noticeable.

Exhaust silencers do add some backpressure that could theoretically reduce gas mileage – but in practice, the impact is not noticeable.

As someone who has tried removing their exhaust silencers through muffler delete on multiple cars, I can tell you that you can gain minor horsepower on the dyno. However it’s not significant enough to be noticeable when you ride. 

Also, I did not notice any gas mileage gain or loss after removing the exhaust silencer. Although, the sound from my car improves significantly. 

In this article, I am going into detail about exhaust silencers – especially when it comes to performance, gas mileage and potential engine damage. 

Sounds interesting? I know it is! 

Exhaust Silencer: Muffler Vs Resonator Vs Baffle Insert

Before we continue further, let’s first talk a bit about the different types of exhaust silencers – there are mainly 3 of them and they each work a little differently.

 

Muffler 

Muffler is a sound suppression device, located at the back of the exhaust – right before the exhaust outlet. 

Muffler is larger than a resonator or baffle insert and is most effective when it comes to sound suppression. 

Muffler works by using several metal plating that’s positioned to bounce sound waves into each other where they cancel.

This means exhaust gases will have difficulty flowing through these plates. Thus, increasing backpressure. 

“Muffler delete” is very popular among horsepower enthusiasts. This is where they cut out the muffler and replace it with a straight pipe instead. 

This makes your car significantly louder and provides minor horsepower – 5 to 10 horsepower, depending on the size of your engine. 

Image of the internals of a muffler

Muffler contains metal plates – designed to bounce sound waves and make them cancel each other out. This design increase backpressure.

Resonator

Resonator is another sound suppression device that’s usually installed alongside the muffler. A resonator only eliminates certain sound frequencies to tone down the sound of your car and make it sound more pleasant. 

This is slightly different from a muffler because a muffler is designed to reduce the overall sound of your car, instead of just silencing specific frequencies. This is why a muffler works better as a sound suppression. 

Resonator is a hollow tube with sound absorbent material inside – like fiberglass. This means as sound passes through, they are absorbed by these materials and disappear. 

A little different than a muffler, where sound waves are made to bounce and collide with each other to cancel out. 

Depending on the states you live in, a resonator might not be required. Most laws state that you need at least one sound suppressing device installed – usually being the muffler. 

Resonator

Resonator absorbs sound waves as they pass through.

Baffle Insert

Baffle insert is a small sound suppression device that you insert into your car’s exhaust pipe. This does not come with stock exhausts and is usually purchased separately to further reduce a car’s sound. 

Baffle insert is more common in a motorcycle’s exhaust – where big mufflers or resonators cannot be equipped. 

Baffle insert should not have any impact on horsepower or gas mileage of a car. It’s a very small and light device that works well to silence car sound but won’t cause any significant change to alter horsepower or mileage.

Baffle insert

Baffle insert is inserted into exhaust tip to silence exhaust noise.

Does Exhaust Silencer Reduce Performance?

Exhaust silencers can slightly reduce car performance – usually by 5-10 horsepower. This happens because exhaust silencers increase exhaust backpressure which can reduce your horsepower. 

Long story short, a car uses air and fuel in the combustion chamber to generate power. The more air and fuel there is, the more horsepower you can get. 

When a combustion happens, exhaust gases are created as byproducts – which take up space in the combustion chamber!

We need to get rid of the exhaust gases from the combustion chamber as quickly as possible, to allow more room for air in the next combustion.

anatomy of combustion chamber

Backpressure prevents exhaust from leaving through the exhaust valve.

Exhaust silencers create additional restriction in the exhaust pipe – which means pressure is increased and exhaust gasses cannot flow out as quickly as they could be. 

Which muffler is your car right now?

This means some exhaust gases remain in the combustion chamber and unnecessarily occupy space. Thus, reducing horsepower.

Remember, all these are in theory. In practice, the backpressure created is not that significant. By removing the exhaust silencers like muffler or resonator, you can gain additional 5-10 horsepower. 

Not so significant and noticeable for the regular street drivers. But this is quite good if you care about horsepower or if you are racing on track. 

When removing exhaust silencers through muffler delete or resonator delete, expect to gain more power when driving at a higher RPM range – this is more noticeable on cars with big engine blocks. 

Does Turbo Muffler Delete Increase HP

Exhaust silencers impact turbo cars the same way it impacts NA (non-turbo) cars. You can gain some minor horsepower by removing the muffler or resonator from a turbo car. 

That being said, turbo muffler delete is not the same as regular muffler delete. Muffler delete means removing the muffler on the exhaust system. We talked about this extensively above.

Turbo muffler delete is where you replace the turbo outlet into an aftermarket one.

An aftermarket turbo outlet is less restrictive and allows exhaust gases to flow out quickly. Thus, reducing backpressure.

If you don’t know how a turbo works, you can go to my article here. Which Is Better: Turbocharger Or Supercharger? 

A turbo muffler delete does not increase horsepower by a lot (maybe even none).

However, it will help you with improving the turbo response. This means your turbo lag is reduced – expect to feel the turbo kicking in at lower RPM.

Turbo muffler delete

Turbo muffler delete (black) is less restrictive and will replace the turbo outlet. This allows exhaust gases to leave quicker.

Does Exhaust Silencer Impact Mileage?

Exhaust silencer does not impact mileage at all. Exhaust silencers like mufflers and resonators are not heavy enough and they don’t create enough backpressure to improve mileage.

If mileage is your worry, then rest easy. Your mufflers or resonators will not lower your mileage in any way. 

If you have mileage issues in your car, exhaust silencer is most likely not the cause. Look into other factors like a rich air/fuel mixture, malfunctioning oxygen sensor or even your driving habits!

I cover more about this topic in this article – where I go through the common myths about muffler deletes and mileage. Muffler Delete & Gas Mileage (Everything You Need To Know)

Is Exhaust Silencer Bad?

Exhaust silencer is not bad and will not damage your car engine in any way. You are recommended to have at least one exhaust silencer in your car to legally drive on the street. 

Most cars from the factory come equipped with at least one exhaust silencer (a muffler or resonator). This indicates that they are designed to work well in your car and will not cause any damage. 

Removing the exhaust silencer from your car also will not cause any damage. Air/fuel ratio and backpressure will be altered slightly – but not significant enough to cause any change or damage. 

However, removing the exhaust silencer will make your car sound extremely loud – even deafening at times. From my experience, the sound gets boring and irritating after some time.

Plus not to mention how much trouble you will get from the traffic cops. I recommend only doing muffler delete for your weekend traffic cars. 

Here’s a YouTube video comparing the sound before and after a muffler delete. It may sound cool now, but trust me.. It gets boring and irritating real quick. 

Should You Install Exhaust Silencer Or Remove Them?

Now that you know quite a lot about exhaust silencers – the question becomes should you remove them? Or install an exhaust silencer that’s suitable for you?

 

Advice: Removing Exhaust Silencer

If you are a person that likes an aggressive and loud exhaust sound, then removing the exhaust silencer is one of the cheapest methods you could go for.

I recommend looking into removing only the resonator. Some cars come with both resonator and muffler. 

By removing only the resonator, you are still driving legally and your car will sound more aggressive.

If your car only equips a muffler, then removing the muffler for a more aggressive sound is also an option. 

However, the exhaust sound could become too loud and deafening. Not to mention it’s illegal in many states.

Related Article: Muffler Delete Vs Resonator Delete

Advice: Removing Exhaust Silencer

If your car only equips a muffler (no resonator), then my suggestion is to replace the muffler instead of removing it completely. 

With an aftermarket performance muffler, you can still drive legally while achieving the exhaust sound that you are looking for.

There are many options for performance mufflers – ranging from a little loud to extremely loud. The key is finding out what kind of sound you want and then finding the performance muffler for it. 

Personally, I would go for a performance muffler that provides sound improvement but not terribly loud at the same time. I cover my muffler recommendation and tips about buying mufflers in this article.

Best Muffler: Which To Get & What To Look For?

Ifandi S.

Ifandi S.

Passionate about everything mechanical. Ifandi has been involved with motorcycles and cars since the old days - in his family's auto parts shop. Want to keep in touch? Scream "STRAIGHT PIPEEEEE" at the top of your lungs and Ifandi will show up.

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