Can drilling holes improve a car engine sound? Even if it can – what about the pros and cons? Will there be any long term damages? Let’s discuss everything in detail.
Quick answer – Yes. Drilling holes in your exhaust will definitely make your car louder. By doing so, you allow some sound waves to escape before they are silenced by the muffler. It’s important to drill holes at the right location to prevent damage to the car.
Where does the exhaust sound come from?
Let’s brush up our knowledge a bit. Exhaust sounds come from the car’s combustion chamber. To deliver power your car needs to generate combustion by igniting fuel in the combustion chamber.
Every combustion generates toxic gases and huge sound waves. These toxic gasses and sound waves will exit into the exhaust system and eventually out of the car.
While traveling through the exhaust system, the sound waves will go through a muffler before it exits the car. A muffler’s job is to reduce the sound waves so that your car will not make too much noise.
Car manufacturers will try to eliminate the noise as much as possible to meet government regulations and to ensure the car is attractive for the largest audience.
How does muffler work?
Sound waves can be eliminated by having them cancel each other. This works by introducing an equal sound wave at the opposite direction of the initial waves.
A muffler’s main job is to reverse the direction of sound waves so they collapse into each other and cancel out.
A muffler’s internals consist of sophisticated channels, holes and tubes – designed to create walls that cause the sound waves to bounce and reverse into each other.
Here’s the internal of a muffler.
Why drill holes in an exhaust?
People usually drill holes on their exhaust system to improve the sound of the car (Strange things that people do…).
Sound waves that travel through the exhaust will have an early exit into the atmosphere through the holes.
These sound waves do not go through the muffler and get silenced. Thus, the engine sound that is heard is much louder and more aggressive.
Drilling holes in your exhaust can be a cost effective way to improve the sound of a car. All that you need is a drill and the drill bit. ⅜ inch drill bit is recommended.
Where should the holes be?
To avoid any damage and problems to your car, it is important to drill the holes after the catalytic converter. And right before the muffler.
After Catalytic Converter
A catalytic converter is used to convert toxic exhaust gases into non-toxic ones like carbon dioxide and water vapor.
If you drill a hole before the catalytic converter – that means the exhaust gases can seep out of the exhaust system before they are converted into non-toxic gases.
This could be dangerous to the environment and also to yourself – especially if these toxic gases can seep back into your car and you breathe them.
These toxic gases are especially because they are odorless and colorless. You would not notice them before it’s too late.
After O2 Sensor
You must also ensure that the holes are drilled after the oxygen (O2) sensor. If there are holes in the exhaust before the oxygen sensor – air can seep into the exhaust system and cause the oxygen sensor to sense a false additional amount of oxygen.
Your car’s ECU will assume there is too much air and not enough fuel in the combustion chamber. This will cause your car to inject more fuel unnecessarily and impact your fuel economy in a bad way.
I will mention it again. It is extremely important to drill the holes right before the muffler and right after it has passed the oxygen sensor and a catalytic converter.
How many holes should I drill?
I recommend you to only drill a few holes. If you’re using a ⅜ inch drill bit then six holes around the exhaust is more than enough. the changes in your engine sound would already be apparent.
Here’s the ⅜ inch drill bit from Amazon, if you don’t have it.
The change in engine sound depends on the size of the hole. If you drill smaller holes, then you might need more and vice versa.
Is drilling holes in your exhaust bad?
Failed Emission Test
If you drill holes before the entrance to the catalytic converter, then your car will likely fail the emission test.
Holes before the entrance to the catalytic converter means that toxic exhaust gases can seep out of the exhaust system before they are converted into non-toxic ones.
If your States require you to have a carbon-emission test regularly, then you will definitely fail on this one at some point. So make sure you drill the holes at the correct location.
After the catalytic converter and right before the entrance to the muffler. See the illustration above.
Bad Fuel Economy
Holes around the O2 sensor will cause the sensor to have an inaccurate reading. Additional air can seep in and cause your O2 sensor to detect a higher Oxygen reading.
Your car’s computer will assume there’s too much Oxygen and too little fuel – causing your car to unnecessarily inject extra fuel that will not burn off and be wasted. This will increase your car’s fuel consumption in a major way.
Does drilling holes in my exhaust really make it louder?
Drilling holes in your exhaust will definitely make it sound louder. This is because some of the sound waves will be able to escape to the atmosphere before they could be silenced by the muffler.
This will cause your car not just sound louder but it will also sound more aggressive. The change of sound could be immediately noticed right after you drill the holes in the exhaust.
Check out this YouTube video below to heard the before and after sound.
Should I drill holes in my exhaust?
I do not really recommend you to drill holes on your exhaust. It could seem cheaper in the beginning because you do not have to buy any new equipment to make your car sound louder and more aggressive. However, the potential problems could end up costing you more in the long run. The worst case scenario is that you have to replace the entire exhaust system and you also will suffer from illness because of the toxic gases seeping into the internals of your car.
Other ways to make your exhaust louder
Cold air intake
If you really want a louder and more aggressive sound of your car but do not have budget I recommend you to look into cold air intake instead. The sound improvement will not be as apparent as drilling holes.
However you will notice a more aggressive sound when you accelerate. Furthermore, a cold air intake will also improve the performance of your car slightly.
A cold air intake is cheap to install at a few hundred dollars and is also easy to install
Muffler delete is basically removing the muffler from your exhaust system. This means the muffler won’t be available to reduce the noise from the combustion chamber – causing a louder engine sound. This is another cost effective way to make your car sound louder and more aggressive. All you have to do is take out the muffler from the exhaust system by unscrewing some bolts and then weld a pipe to the exhaust to replace the muffler.
Although, you have to be careful with the laws of your State. A lot of states require your car to at least have one sound suppression device installed.
An exhausts system usually has two sound suppression devices: muffler and resonator.
This technically means you can remove the muffler while still being legal to drive. However please check with your local laws about this before deleting your muffler!
Here is a YouTube video showing you how to delete your muffler.
Resonator Exhaust Tips
Resonator exhaust tip is another cheap and proven way to make your car exhaust sound louder. It won’t be as loud as muffler delete. However, this is Legal in most states and is easier to install. Resonator exhaust tip is installed at your tail pipe. It works the opposite way as a muffler.
Still remember that mufflers cause sound waves to cancel out each other? Resonator exhaust tip is a hollow Chamber that will cause sound waves to vibrate in a certain way to produce more sound.It is usually easy to install where you just have to screw them on your exhaust tail pipe.
That’s it! I hope this article has been a good read to you. If you are interested in more car stuff, check out my other articles 🙂