Are Bigger Exhaust Pipes Louder?

By October 18, 2020Exhaust, Muffler

Aftermarket exhaust that you see on loud cars are often bigger than the stock ones. Are they bigger because of the sound? Or something else? Let’s discuss the size of exhausts and the sound they make in this article.

If you are too lazy for the details, bigger exhaust pipes do make the exhaust louder – but only by a little. Exhaust pipes are made bigger to allow better exhaust flow. This is important for increased performance and horsepower (not for the sound). Instead, aftermarket exhaust also equips a less restrictive muffler – which is responsible for the much louder sound. 

I guess you still have many questions like ‘How does a bigger exhaust pipe increase performance?’ or  ‘Why does a bigger exhaust pipe not improve sound by much?’ I will cover all these questions in detail. So read on 🙂

Recap: What Generates Exhaust Sound?

Let’s first talk about exhaust sound – where do they even come from? To produce power, your car needs to generate combustion in the combustion chamber. This combustion is a controlled explosion that in turn generates power, loud sound and exhaust gases. 

After every combustion, the sound waves and exhaust gases exit the combustion chamber and enter the exhaust system – where they eventually exit the car. Without any suppression, the combustion noise is extremely loud – where it becomes a nuisance and even illegal.

This is why car manufacturers equip mufflers in their exhaust system. Muffler, as the name suggests, muffle the combustion sound. It works by making sound waves bounce and collide into each other where they cancel out (pretty sciency stuff right there).  

So if you want a louder exhaust sound, you need to tweak the muffler. If you are wondering, ‘if I remove the muffler from my exhaust, won’t my exhaust sound be super loud and aggressive?’ That’s actually right.

Removing the muffler from the exhaust system is called muffler delete. It’s a cheap way to make your exhaust sound much louder but it’s extremely loud and illegal in some states in the US. I have an article here that talks about muffler delete in detail and also its impact on fuel consumption. Give it a read if you want to know more.

What Does Bigger Exhaust Pipe Do Exactly?

I mentioned earlier that if you want a louder exhaust, you should tweak the muffler instead of the exhaust pipe. So now the question is why do people install bigger exhaust pipes in the first place? The answer is horsepower.

I have already told you that a car needs to generate combustion to deliver power. What I didn’t mention is that combustion needs fuel and air (oxygen) to exist. If you want more horsepower, your car needs to generate bigger combustion – which means more air and fuel.

Getting more fuel into the combustion chamber is easy. Your car can just inject more. The problem is how to get more air into the combustion chamber? You can’t just simply inject or suck more because air enters the car naturally from the air intake (through air pressure difference).

Bigger exhaust pipe is one way to increase the amount of air in the combustion chamber. You see, when combustion happens, exhaust gases are produced – which have to leave quickly. Otherwise, they will take up space in the combustion chamber. 

Which means there won’t be enough room for new air to enter in the next combustion cycle. Bigger exhaust pipe makes sure exhaust gases leave the combustion chamber quickly. They create lower air pressure in the exhaust system and force the exhaust gases to leave (air particles always travel from high pressure area to lower). 

With that, the combustion chamber now has more room for more air to enter in the next combustion cycle – resulting in bigger combustion and more horsepower baby! These are just a brief explanation. If you want to know more, give my other article a read. Does Aftermarket Exhaust Add Horsepower? 

anatomy of combustion chamber
Air enters combustion chamber from air intake.
Fuel is injected into combustion chamber.
Combustion is generated that will push piston down to move wheels.
Exhaust gases leave combustion chamber into exhaust system because of air pressure difference. Bigger exhaust pipe decrease pressure in exhaust system, so more exhaust gases will escape.

Why Is Bigger Exhaust Pipe Louder?

By now you should understand that bigger exhaust pipes are used to increase horsepower and not for louder sound. But what if I told you bigger exhaust pipes also help in louder exhaust? Not by much, but it will be louder. 

Earlier I told you mufflers work by making sound waves bounce into each other and cancel out. Which means if there are more things on the way, sound will be muffled (softer). This is why an empty house makes you sound louder than a fully furnished house.

This also applies to the diameter of your exhaust pipes. Louder pipe means that there is more space for sound waves to spread and out and not get bounced into each other. Which means they will sound louder.

But again, not so much louder because bigger exhaust pipes will only be 1” or 1.5” wider than stock.

How Big Should My Exhaust Pipe Be?

The good thing about aftermarket exhaust is that they will most likely include a less restrictive exhaust as well. Making your car more powerful and also louder.

Choosing an exhaust for the sound is easy. You can just hear the before and after sound from YouTube videos and make your pick. Choosing an exhaust for the performance is harder – bigger exhaust pipes don’t always mean more horsepower. Exhaust pipes that are too big for your engine can make you slower instead!

Exhaust pipes that are too wide allow exhaust gases to escape from the combustion chamber but they will flow very slowly (low exhaust velocity). Exhaust pipes that are too narrow allow exhaust gases to flow quickly but they won’t move from the combustion chamber into the exhaust systems. 

This means you need to get an exhaust system with pipe that’s not too narrow or too wide. As a general rule, the diameter should be measured against your engine horsepower. Exhaust Diameter in inch = Horsepower / 100. For example, If your car has 250 horsepower, you should get an exhaust that’s 2.5”.

This ensures you gain horsepower from your aftermarket exhaust.

image of flowmaster axleback exhaust
Exhaust pipe diameter should be measured on the pipe. Not the exhaust tip.
This is exhaust tip. Don’t measure the diameter of exhaust pipe from here.

Best Ways For A Louder Exhaust

If all you look for is a more aggressive sound, then below are the easiest and cheapest ways you could do. They are also very effective. 

  1. Performance Muffler
  2. Drill Holes In Exhaust
  3. Resonator Exhaust Tip 
  4. Cold Air Intake
  5. Muffler delete 

If you want to know the details for each of them, then check out my other article. 5 Ways To Make Your Car Louder For Cheap.

My Recommendation

Performance Muffler

If you want a louder sound, the most effective way is to replace the muffler. You don’t have to replace the entire exhaust system – just the muffler is enough.

A good performance muffler cost about $100 to purchase and maybe another $25 to install at your average car workshop. This is a very good investment considering the sound improvement they provide (see the video below for the sound of performance muffler). 

I personally recommend the Flowmaster Super 40 muffler. They will make your car sound more aggressive and louder but not to the point where it’s deafening and illegal. Also, the guys from Flowmaster have been in the muffler and exhaust space for a long time – so you are in good hands. 

I have an article here where I talk about what you should look for when buying a performance muffler. Check it out if you are thinking of buying one. Best Performance Muffler: Which To Buy And What To Look For?  

Here’s a YouTube video showcasing the before and after of the Super 40. Pretty aggressive and not so loud – just how I like it 🙂 

Performance Exhaust

If you want both horsepower gain and also the sound, then I recommend you go for performance exhaust. It’s way more expensive than just a muffler but is a must buy if you want the performance gain. 

For performance exhaust, I also recommend the Flowmaster exhaust – specifically the Flowmaster Force II series. They will make your car sounds aggressive as hell without being too loud and illegal.

I also have an article where I talk about the things you should look for when buying performance exhaust. Check it out if you are interested. Best Exhast: Which To Buy And What To Look For? 

Ifandi L.

Ifandi L.

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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