The Dos and Don'ts of a DIY Exhaust

Date Posted: 13 February 2025

Building your own DIY exhaust system is definitely an exciting project, especially if it’s your first go. You can personally boost your car's performance and give it a unique sound, but DIY exhaust systems can be a bit intimidating at first. However, with the right planning, tools, and knowledge, you’ll have your vehicle sounding and performing better in no time. Just remember, a successful DIY exhaust project is all about preparation and precision - so let’s dive in!

The Most Important Step - Plan Ahead

Before you even think about cutting or welding, planning your DIY exhaust system is essential. A well-thought-out plan will save you time, money, and frustration. Without a good plan in place, there’s little chance that your DIY exhaust will fit properly and perform the way you want. In general, you first need to decide what type of exhaust you want to install. The most common types are single-pipe and dual-pipe exhaust systems.

A single-pipe system is simpler and often more cost-effective, while a dual-pipe system provides a more aggressive look and may offer better performance for higher-powered engines by allowing exhaust gases to flow more freely. Another decision to make is between axle-back, cat-back, and turbo-back exhausts. A cat-back exhaust is the most popular upgrade, replacing everything from the catalytic converter to the rear of the vehicle.

It improves exhaust flow, boosts performance, and gives you the signature sound. That being said, for performance-oriented vehicles, a turbo-back system is probably the best choice. A turbo-back includes everything from the turbocharger (if you have one, of course) all the way to the tailpipe, offering the most significant performance gains for turbocharged engines.

However, if you’re not looking to replace everything and just want to improve sound and performance from the rear end while saving some money, an axle-back system might be your best bet. This system only replaces the parts from the axle back, making it a more affordable and less involved upgrade. When you get into the specifics, the first thing to consider is pipe diameter. The size of your exhaust pipes directly affects performance. If the pipes are too small, they can restrict airflow and limit power gains. Too large, and you might lose low-end torque.

A general rule is to match the diameter to your engine’s displacement and power output - bigger isn’t always better. Next, think about sound. Do you want an aggressive growl, a deep rumble, or something close to stock? Your choice of mufflers, resonators, and even pipe routing will determine how loud or quiet your exhaust will be. Straight pipes are loud but can drone at highway speeds, while chambered or turbo-style mufflers help manage noise without killing performance.

Routing the pipes is another crucial step. Factory exhaust systems are designed to fit perfectly under the car, but a custom setup might require some creativity. You need to ensure the pipes clear suspension components, fuel lines, and the undercarriage. The last thing you want is a pipe that rattles against the frame or drags on the ground.

Exhaust pipe material choice is also important. Stainless steel lasts longer and resists rust better than aluminised steel, but it is more expensive. If you live in an area with harsh winters or high humidity, investing in stainless steel might be worth it (many parts of Australia are rather humid, so a stainless steel DIY exhaust is generally a good investment).

Suspension points matter too. Your exhaust system needs to be securely mounted to prevent excessive movement, which can lead to stress fractures or annoying rattles. Using quality exhaust hangers will keep everything in place and minimise vibration. Finally, decide how many silencers you’ll install. If you’re going for a performance setup, you might opt for a single high-flow muffler.

If you want a quieter ride, adding a resonator can help cut down on noise without restricting performance. Once again, taking the time to plan ahead ensures that your DIY exhaust project goes smoothly. Rushing in without a plan can lead to costly mistakes, wasted materials, and a system that doesn’t perform the way you expected.

OEM Parts vs. Aftermarket Parts

A large selection of car parts for DIY exhaust projects.

You also need to decide whether to use OEM (original equipment manufacturer) parts or aftermarket parts. OEM parts are the same components that came with your vehicle when it was built. They’re designed to fit perfectly and maintain factory performance standards, but they can be pricey and sometimes lack the customisation options you may want for a DIY project.

On the other hand, aftermarket parts are designed by third-party manufacturers and often offer better performance, durability, and variety. They’re typically more affordable, and you can choose from a wide range of options to suit your specific needs, whether that’s optimising power, changing the sound, or improving efficiency. In short, aftermarket parts are generally the better choice for a DIY exhaust system, as they provide more flexibility for customisation and typically offer better value for the money.

Measure Everything Twice Before You Order

Once you decide what you need for your DIY exhaust, do a double-check. Before you hit buy on those exhaust parts, make sure you measure everything twice. A common mistake in DIY exhaust projects is ordering parts without double-checking measurements, which can lead to frustration and delays. The last thing you want is to find out that the pipe diameter is wrong or that the parts don’t fit when they arrive.

Measure the length, diameter, and angles of the pipes, and account for any bends or tight spaces under your car. Also, don’t forget to check the mounting points and exhaust hangers. Taking the extra time to measure twice will save you from costly mistakes and make sure everything fits properly when it’s time to start welding.

Assembling the Parts

Now that you’ve got all the parts you need and everything fits, it’s time to start assembling your DIY exhaust. This is where the real work begins. Welding is the heart of any custom exhaust build, and there are two primary methods you’ll encounter: MIG and TIG welding. MIG (metal inert gas) welding is more commonly used for home projects because it’s easier to learn and faster to execute. It’s ideal for beginners and works well with thicker metals.

TIG (tungsten inert gas) welding, on the other hand, offers cleaner, more precise welds and is preferred by professionals. While TIG welding requires more skill and patience, it’s perfect for intricate work and gives you a cleaner, more durable finish, which is particularly important for high-performance setups. Regardless of which welding technique you choose, make sure your welds are strong and clean to avoid leaks and ensure your exhaust system performs as it should.

A sloppy weld might look okay at first, but over time, it can cause problems with airflow or even lead to exhaust failures. Keep the welds consistent and pay attention to the heat settings and welding rod choice to ensure a strong, lasting bond. Remember, assembling the parts also includes ensuring proper alignment and fitting.

You don’t want any pipes that are misaligned or sitting at an odd angle - this could affect performance and even cause rattling or clanging sounds. Take your time, and be meticulous with each step. Your hard work here will pay off when you fire up your car with a custom exhaust that not only looks great but performs just the way you want.

Buy Affordable Aftermarket Parts Online

If you have your heart set on building a DIY exhaust system, we have all the parts you could need. At Perform-Ex Auto, we sell high-quality performance exhaust parts as well as standard replacement parts. All of our products come with a manufacturer’s warranty so you know you don’t have to worry about durability. You can order everything online and we’ll send everything right to your address.

However, we would still urge you to contact us if you are unsure about something. DIY exhaust projects can be complicated, but our team has decades of automotive experience - we can answer any questions you have and help you make the best choice. Until then!