Drilling a hole in a muffler is often done to change the sound of the muffler. Baffles inside the muffler act to reduce noise and improve airflow. However, if you’d like to drill a hole in your muffler to alter the airflow dynamics of your muffler and to make the car louder, you’ll need to know do this.
1. Slide the 3/8-inch drill bit into the drill chuck and tighten the chuck by turning it counterclockwise.
2. Set the drill bit against the bottom of the muffler. It really doesn’t matter where you drill the hole, but if you want to make sure that moisture does not collect inside the muffler, drill on the bottom of the muffler.
3. Set the drill speed to “slow” and begin drilling. Once you have started a groove in the muffler bottom, increase speed until the bit punches through the muffler. You can drill more than one hole in your muffler, but using a smaller drill bit allows you to control how loud the muffler will get. If you want a louder muffler, simply drill more holes.