The Key Parts of Exhaust Systems and the Different Types of Systems
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Close-up of 2 Toyota Hilux

The Key Parts of Exhaust Systems and the Different Types of Systems

Is the DPF in your Hilux clogged, and there’s no chance of regenerating it? Well, you’re probably looking at a brand-new DPF Hilux exhaust. Contrary to what many people think, you don’t have to replace your entire exhaust system when replacing the DPF. Exhaust systems are made of quite a few components, which I’ll discuss so you get a better understanding of what the different types of exhaust systems are. 

As a general rule of thumb, when replacing your factory exhaust system, you want to replace as much of it as possible in order to get the most performance out of the aftermarket exhaust. However, if you’re on a budget, you don’t have to. Having said that, the main types of exhaust systems are cat-back, axle-back, header-back and DPF-back.

Major Parts of an Exhaust System

Mechanic beside hsi Hilux holding exhaust pipe


The headers are the first exhaust parts that handle exhaust gases once they leave the engine. Headers are also called manifolds in their stock form, and they’re directly bolted onto the cylinder heads. Aftermarket headers are usually mandrel-bent to reduce gas flow restriction, allowing the exhaust gases to move unobstructedly from the engine. As a result, you won’t get backpressure and will get improved exhaust flow velocity that will help the system scavenge exhaust gases from the engine.

Catalytic Converter

The catalytic converter is responsible for eliminating the harmful emissions that come from the burning of fuel. Every vehicle is equipped with one, with diesels like your Hilux having a DPF on top of it. The DPF Hilux and cat work together to reduce the harmful gasses into oxygen, water, nitrogen and carbon dioxide before they’re released from the atmosphere.


The muffler is responsible for reducing the noise that comes out of your exhaust system. While it sounds like a straightforward job, things can get quite complicated. Mufflers use a variation of chambers, perforated tubes, sound-deadening materials and baffles to accomplish this. Manufacturers configure these different parts in different ways in order to produce different exhaust sounds. 


Downpipes are the first pipes that connect the headers to the mufflers. Somewhere along the way, you’ll find the catalytic converter. 

Then, there are crossover pipes, which are designed to balance the exhaust flow in dual exhaust system applications. They’re generally installed near the headers, and their job is to reduce the uneven exhaust flow from the engine cylinders by providing an avenue to the exhaust pulses, allowing them to travel between the two sides of dual exhausts. As a result, you get reduced back pressure. Crossover pipes are available in X and H variations. The reason they’re named X-pipes or H-pipes is due to their shape. 

Lastly, you have tailpipes, which are the last piece of the exhaust system. They’re located after the muffler, going to the rear side of your vehicle. The tailpipes are the only part of the exhaust system that’s visible, which is why they’re typically made from Chrome or are polished, and are available in a wide range of shapes and finishes.

Types of Exhaust Systems

CLose-up from underneath of a Toyota Hilux

Header-Back Exhausts

Header back exhaust systems are a full replacement for your stock exhaust and come with all the aforementioned parts. This allows you to increase the diameter of the whole system, providing greater flow. Naturally, these systems are the most expensive as a result and more difficult to install.

Cat-Back and DPF-Back Exhausts

These systems replace the exhaust parts from the DPF or catalytic converter to the tailpipe. Generally, kits will include a muffler and tailpipe, and depending on the kit, they may include H-pipes, X-pipes, Y-pipes or mid-pipes. These exhaust systems are popular because they’re relatively easy to install, yet provide a good bang for your buck. Of course, how much you get out of them will depend on the design of the converter and the rest of your stock exhaust parts. 

Axle-Back Exhausts

These exhausts only replace the parts from the rear axle to the exhaust tip. While you won’t get a lot of power gains, you’ll get an easy-to-replace system that enhances your vehicle’s sound and looks.

Single vs Dual Exhausts

Another important consideration when replacing your stock setup. Single exhaust systems are the most common setup, and they feature a single set of exhaust parts, including a muffler and tip that sits behind the vehicle’s axle. These systems provide a decent performance upgrade as they come with larger diameter pipes and mandrel bends. They’re also more affordable and lighter in weight than their dual exhaust counterparts.

Dual exhaust systems feature a similar setup, but they have two exhaust tips that go out from the muffler. There’s no real performance benefit to this design, but some people prefer them due to their looks. There are systems known as true dual exhaust systems, which feature two pipe sections from the header to the tip, as well as two catalytic converters, and two mufflers. This setup provides a sportier look, a distinctive sound, and high-flow performance.

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