Muffler Vs Catalytic Converter: Differences, Horsepower & Cost

The aftermarket muffler makes less sound suppression and increases the car sound, making your car loud and aggressive but at the same time, the aftermarket muffler doesn’t add any horsepower.

Whereas an aftermarket catalytic converter referred to as “High Flow” is responsible for making your car’s exhaust less restricted. Less exhaust restriction adds more horsepower to your car – 15 to 30hps.

Sometimes choosing the right mod for your car is a hard task and it could be confusing. Both muffler and catalytic converters are easy and effective mods but where to start first?

Because I have done both mods and I have tried on a couple of different cars, I can tell you that a catalytic converter is more effective in terms of power gain. But it has a few drawbacks which I’m going to tell you.

In this article, I’m going to do a comparison of mufflers vs catalytic converters in detail. We will cover differences, horsepower, cost, and much more:

  1. Difference between muffler & catalytic converter
  2. How do they work?
  3. Muffler Vs Cat Delete
  4. Horsepower Gain
  5. Warranty
  6. Legal
  7. Aftermarket muffler and catalytic converter
  8. Cost

Is The Muffler and Catalytic Converter The Same Thing?

Muffler and Catalytic converter are two different parts of an exhaust system. Mufflers are used to reduce the loud exhaust sound and Catalytic converters are used to filter out harmful emission gasses that come out of the exhaust.

A lot of people get confused between Muffler and Catalytic converters and they think that both are the same. Muffler and catalytic converter both are connected to the same exhaust system but yet they function on their own. They are designed to work on their own, which means that deleting a muffler or deleting a cat won’t affect each other.

Since both parts are under the vehicle, it’s a hard thing to understand when you haven’t even seen one in your life.

Here’s a picture of the Muffler and Catalytic converter to give you an idea of what they look like.

turbo mufflers


catalytic converter internal view

catalytic converter

You can easily differentiate between the muffler and catalytic converter judging by their looks and their position on the exhaust system. A Muffler is located at the very end of the exhaust system — usually at the back of your car.

A catalytic converter is located between the exhaust header and the muffler.

Muffler Vs Catalytic Converter

Muffler Delete Cat Delete
Horsepower gain 5 Horsepower 15-30 Horsepower
Backpressure Reduced Reduced More
Performance improvement Less Exhaust restriction Less Exhaust restriction
Sound Louder Loud
Fuel efficiency (MPG) No affect Minor Improvement
Tune required  No Must Need
Legal No No
Installation Easy Easy
Suitable for turbo Yes Yes
Delete Cost 50-100$ $50-300 (without tune)

$500-1500 (with tune)

Aftermarket Muffler Aftermarket Catalytic converter
Cost $80-300 $60-400
Horsepower gain 5hp 15-30hp
Legal Yes Yes

Position On Exhaust: Muffler Vs Catalytic Converter & Pre cat

The Muffler is always located at the end of the exhaust system of your vehicle.

A catalytic converter has two positions on the exhaust system, one is the main rear cat and the other one is called pre-cat. The front Cat is close to the engine and the rear cat sits in the middle or rear side of the car.

professional inspecting car muffler

As you can see in the picture above, a guy is holding a muffler which is located at the back of the car. Some cars have side exhausts and, in that case, the muffler position will be changed from rear to mid.

Generally, catalytic converters are at the middle or rear side of the car. Few cars have more than 1 catalytic converter which is called pre-cat.

Pre-cat is also a catalytic converter, but it’s located at the front side of the car. Pre-cat is directly mounted to the engine’s exhaust manifold and its job is to work as a supplementary converter for the main catalytic converter.

The pre-cat does the early conversion job so well but because it’s closer to the engine it gets really hot and runs out fast.

READ MORE: Does Aftermarket Exhaust Add Horsepower?

How It Works: Muffler Vs Catalytic Converter 

The muffler is responsible for reducing the sound waves that come from the engine. Muffler works by combining sound waves in a way that they cancel out each other.

A Catalytic converter reduces harmful emissions like carbon monoxide, hydrocarbons, and Nox2.


A Muffler basically has 4 important components, and it works very simply.

  1. Outer body
  2. Sound Dampen Layers
  3. Inlet and outlet tube
  4. Chamber plates

The outer body of a muffler works as a heat shield, and it protects inside layers and tubes in the muffler. 

The sound dampens layers, absorbs sound waves, and softens the engine sound. The Inlet tube is the most important part which does all the magic of silencing your car.

The exhaust gas comes through the inlet tube and then escapes through the holes. The chamber plate bounces the sound waves into each other. This action reduces the loudness of the engine exhaust and makes your car silent. The exhaust gas leaves the muffler through the outlet tube which is connected to the exhaust tip.


Catalytic Converter

Catalytic converter or a cat reduces the number of harmful gasses your engine is making after the combustion. Exhaust gasses contain Carbon monoxide, hydrocarbons, and nox2. These gasses are harmful, and they also cause Air pollution as a result of smog. 

A catalytic converter sits in between the exhaust header and muffler and converts harmful emissions into breathable Air.

A catalytic converter has a Ceramic structure which helps in the conversion of emissions once it gets hot.

The exhaust gas first goes through the reduction catalyst where platinum and rhodium metals pull oxygen from nitrogen.

2nd is the honeycomb pattern catalyst where separated oxygen molecules are turned into CO2.

Then the gas goes to the last one which is an oxidation catalyst where the unburnt hydrocarbons get removed before leaving the catalytic converter.

Catalytic converters have reduced the emission to 70% since we have started using them. Now it’s a part of the law that your car must have a catalytic converter if it’s running on a combustion engine.

Horsepower gain: Muffler Delete Vs Catalytic Converter Delete

The Muffler delete does add minor horsepower (About 5hps). Whereas the Catalytic converter is more efficient and adds about 15 horsepower. It can go up to 30hps after a tune. Horsepower gain after cat delete often depends on engine displacement, a bigger engine like v12 would get more horsepower gain – up to 60hps.

After the cat delete the car gains more horsepower as compared to a muffler delete. the way catalytic converters are designed from the inside is responsible for causing Air restriction in the exhaust system. Exhaust gasses would have to pass through a honeycomb pattern catalyst before leaving the exhaust system.

When the exhaust air goes through small gaps it becomes more restricted. Due to the restriction, the engine cannot take more air and produce more power.

Removing the catalytic converter means reducing exhaust restriction – allows the engine to make more power and it can go up to 30hp gain after the tune.

The muffler on the other hand is not much responsible for reducing engine power. The muffler does affect horsepower but it’s minor on the scale and definitely not higher than the catalytic converter.

The muffler is responsible for making your car silent. It muffles the sound waves coming from the engine and this process does create back pressure which reduces around 4-5hps. Thus, the horsepower gain from a muffler delete is not much.

However, if you have a streetcar and horsepower is not your aim then I would suggest going with a muffler delete because it’s fun, easy, and makes your car loud.

Note: Make sure about the laws of your area before performing any exhaust mode. 

RELATED ARTICLE: Catalytic Converter Delete 101: Horsepower, Sound & Cost 

Legal: Muffler Vs Catalytic Converter

Installing an aftermarket Muffler or catalytic converter is totally legal as long as your replaced component is not against the law.

Few aftermarket mufflers can be too loud, and they turn out to be illegal.

Aftermarket cats are legal, and they should have the right certification to pass smog inspection. Either it should be an H grade, or an OEM grade certified to pass the emission test.

Note: When it comes to muffler delete or cat delete, it’s totally illegal to do because the cat delete won’t pass emission control tests and the muffler delete won’t pass the sound test.

It is recommended to ask the professional seller before installing any Aftermarket mod, they will guide you according to your vehicle.

Warranty: Muffler Vs Catalytic Converter

Both muffler and exhaust will void the warranty of your car at a certain level. Exhaust modifications like Muffler delete or Catalytic converter delete will completely void the warranty of your car.

Due to the Musson warranty act, a dealer cannot void the warranty by giving false warranty clauses.

To void the warranty of your whole car, a dealer has to prove that the mode you have done is the reason behind your claim. In most cases, cat delete causes the engine failure and voids the warranty. 

Installing an aftermarket muffler or catalytic converter will most likely void the warranty of your exhaust system.

RELATED ARTICLE: Downpipe 101: Horsepower, Engine Light, Sizing & Legality

Aftermarket: Muffler Vs Catalytic Converter

Aftermarket mufflers are commonly used for making cars louder. Most aftermarket mufflers don’t add any horsepower, even if they do it’s not more than 4-5hps max.

Aftermarket Catalytic converters are also known as “High flow” Cats. They are less restricted and add around 15-30hp.

Mufflers are just for reducing the loud engine sound, as I have already mentioned above. Installing an aftermarket muffler won’t make any major difference in performance. Aftermarket mufflers tend to be louder than stock mufflers.

Catalytic converters are more responsible for causing air restriction in the exhaust. Due to those restrictions, the engine cannot produce more power. It’s the only drawback of a catalytic converter. 

Aftermarket Catalytic converters are designed to reduce that air restriction without risking the emissions control. A high-flow Cat will work the same as a stock Cat, but it would be less restricted. It’s also considered the equivalent of Cat Delete even though it does create some exhaust restrictions but it’s safe and legal.

RELATED ARTICLE: Do Mufflers Increase Horsepower: An Expert Weighs In

Watch related video on YouTube:-

Cost: Muffler Vs Catalytic Converter

The average cost for an aftermarket muffler is as cheap as $80 to high as $300. whereas the aftermarket catalytic converter costs around $60 to 400 dollars.

The cheapest cost is when you are installing a cheap muffler or cat on your own.

Both muffler and catalytic converter are available in aftermarket performance variants which are a bit more expensive than the unbranded ones.

If you are installing an aftermarket catalytic converter, then you have to remap your ECU with a new tune that is compatible with your aftermarket cat. This cost is additional and depends on the tuner who’s doing it.

Final Thoughts

In this article we have discussed what is the difference between both cat and muffler. If you are seriously looking for horsepower gain or performance and thinking about choosing either of the exhaust mods, then my suggestions would be to go with the Aftermarket Catalytic converter. Aftermarket cat is a value to money and gives you up to 30hp gain.

However, if horsepower gain is not your main concern and you just want a loud aggressive exhaust then I would recommend you go with an aftermarket muffler. It costs less, it doesn’t require a tune and it’s very easy to install.

Chai WJ.

Chai WJ.

I am a car enthusiast and a passionate rider who loves to discover new places. Since the pandemic, I can't go to places and I started to blog and share information that I learned. I'm not easily distracted, I just... OMG, do I hear a Supra?

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