10 Things to Think About Before Buying an Exhaust System
Here’s What We Cover
- What is an aftermarket exhaust, and should I get one?
- Ten things to consider before upgrading your exhaust system
2.1. The benefits of a stainless steel exhaust system
2.2. Crush bending vs mandrel bending an exhaust
2.3. How thick should an exhaust pipe be?
2.4. Exhaust mufflers and resonators
2.5. What is the best exhaust pipe diameter?
2.6. Exhaust heat reduction
2.7. Will an aftermarket exhaust improve fuel economy?
2.8. Why exhaust systems must come with a catalytic converter or a DPF
2.9. Fitting an aftermarket exhaust
2.10. How to check the quality of an exhaust
When we say ‘Performance Exhaust’, likely the first thing that comes to mind is a deep throaty exhaust note. And you’re not wrong- one of the main reasons anyone replaces their stock exhaust is to get a decent sound out of their 4WD. But there’s still plenty more to consider to get the best bang for your buck.
Factors such as steel grade, pipe thickness/ diameter, and system components will all affect your exhaust’s sound, lifespan, and fuel efficiency. So if you’re in the market for an upgrade, our performance exhaust range has you covered – let us talk you through it.
What is an Aftermarket Exhaust, and why do I Need it?
An aftermarket exhaust increases your system’s lifespan and improves vehicle performance. If you’re running a stock exhaust, chances are it’s either mild steel or 409-grade stainless- inexpensive steels that are easy to fabricate and cheap to produce. While cost-effective for vehicle manufacturers, stock exhausts are prone to rust and restrict sound and performance. So how do you know if your exhaust is ready for an upgrade?
Apart from improving your vehicle’s sound and performance, there are a few tell-tale signs your stock exhaust should be replaced with a performance exhaust:
- Poor fuel economy
- Loss of power and torque
- An unpleasant exhaust note
- High exhaust gas temperatures
- Leaks, rattling, cracking, and rust
10 Things to Consider Before Buying an Exhaust System
With plenty of aftermarket exhaust options out there, it’s easy to buy a cheap system that improves your exhaust note without ticking other boxes like long-term performance and quality. Here are ten things to consider before spending your hard-earned cash on an aftermarket exhaust.
1. Benefits Of A Stainless Steel Exhaust System
Firstly, think about where your exhaust is located. Underneath your vehicle, it’s exposed to the elements plus cycles of extreme heat, pressure, and vibrations. The steel grade of your exhaust will directly affect the following:
- Durability
- Price
- Rust resistance
- Appearance
There are four main types of steel used in exhausts; here’s a look at the pros and cons of each…
The difference between mild, aluminised, 409-grade, and 304-grade steel
To sum it up, the benefits of a stainless steel exhaust are greater strength, rust resistance, and longevity. All Torqit exhausts are manufactured from 304-grade stainless steel, the highest quality steel commonly used in the automotive industry.
Compared to other stainless steels, the high percentage of chromium and nickel present in 304-grade steel give it far superior rust resistance, strength, and a longer lifespan. Plus, you can’t go wrong with a tidy piece of stainless out the back. Learn more here on 304 vs. 409-grade stainless steel.
2. Crush Vs. Mandrel Bent Exhaust Tubing
To transform a straight piece of pipe into an exhaust, it can be either crush bent or mandrel bent. The method used will determine the appearance, performance, and cost of your exhaust …
Crush bending vs. mandrel bending an exhaust explained.
Most OEM exhausts are crush-bent, which is cheaper but looks ugly and restricts performance. At Torqit, our exhaust systems are entirely mandrel bent. Mandrel Bending maximises exhaust flow and guarantees high accuracy, repeatability, and a premium appearance.
With our on-site mandrel bender, Torqit can quickly move from R&D and producing a prototype to modifications and finetuning the fitment. Since our exhausts are designed to accommodate aftermarket accessories such as long-range fuel tanks, chassis extensions, and undertray toolboxes, the millimetre precision of the mandrel bender guarantees that every pipe in the production run will sit precisely how we want it underneath the vehicle. Check out Torqit’s Mandrel Bender in action here.
3. Exhaust Pipe Thickness
The thickness of the steel used in your exhaust will affect both the exhaust note and how much it can handle offroad. The thinner the steel, the more high-pitched and tinny the exhaust note will sound. Check out this video, and you’ll clearly hear the sound difference between thick, quality steel and the tinny vibrations of a cheap, thinly walled exhaust.
Torqit exhausts are among the thickest in Australia, using 304-grade stainless which is 2mm thick and 1.7mm on the bends. This thickness gives the exhaust a nice deep note without cabin drone. To get an idea of how a thick, quality exhaust sounds once installed, check out Torqit’s YouTube channel, which includes a variety of exhaust notes on both DPF-Back and pre-DPF vehicles.
Sound aside, the bottom of your vehicle can take a pretty heavy beating when heading offroad. This means a thin exhaust pipe is more likely to crack and dent. With a thick heavy-duty exhaust system, you can go hard over any terrain, knowing it will handle what you throw at it. If you’re looking for proof, watch Torqit’s 200 Series in action on 4WD 24/7 here. Shauno’s LC200 and Sooty 2.0, Graham’s Y62, and the big MITS79 all run Torqit exhausts and cop everything from gnarly rock crawling to bog holes and rutted hill climbs.
Remember, the thickness of your exhaust is a big indicator of its quality and lifespan. If you don’t want to replace your system every few years, then a thick-walled exhaust will give you the best value for money.
4. Exhaust mufflers and resonators
Two components you’ll usually find in an exhaust system are a muffler and/or a resonator. The key job of a muffler is to quieten or ‘muffle’ the exhaust note, while a resonator acts as a less-restrictive muffler – it stops the exhaust note from being obnoxiously loud.
The inclusion of these on an exhaust system depends first on the vehicle. If your vehicle has a diesel particulate filter (DPF), it’s likely that the noise is restricted. Adding an aftermarket exhaust with a resonator will ensure you get the most sound out of your engine. Check out the note on this DPF-Back Torqit exhaust…
In comparison, adding a muffler to a pre-DPF or cat-back vehicle will keep the volume at an acceptable level and prevent cabin drone when towing or driving long distances. Listen to the note on this pre-DPF Troopy system.
In many instances, a Torqit exhaust will have a combination of mufflers and resonators, i.e. Torqit’s Twin Exit Y62 Performance Exhaust includes two resonators and two mufflers. This helps balance the exhaust note and provides optimum sound across the entire RPM range. The positioning of each component and even the length will also impact the final note, e.g. the resonator length on Torqit’s Twin Exit Jeep Gladiator Exhaust has been custom designed to enhance the note and prevent drone.
Of course, every 4WD owner has their preferences, which is why many Torqit systems have both a loud and quiet option.
5. Exhaust pipe diameter
How big is too big? You might think that the bigger the exhaust pipe diameter, the better the note and flow – but bigger does not necessarily mean better. We know the small diameter of a stock exhaust increases back pressure, restricting exhaust flow and performance. However, too big a diameter and the exhaust flow loses velocity. This will rob your vehicle’s power and performance, reduce fuel efficiency, and produce a less defined exhaust note.
The diameter should be proportional to your vehicle’s engine capacity to get the best performance from your exhaust, i.e. some Torqit exhaust systems are a 3.5″ diameter with a 4″ tip. The larger tip looks tough, while a 3.5″ diameter on the remainder of the system optimises the exhaust note and performance.
6. Heat Reduction
Let’s discuss exhaust gas temperatures (EGTs). Why are EGTs so important? An EGT reading gives you an insight into whether you’re running a rich or lean air/fuel ratio, how hot the combustion process is, and the amount of ‘after burning’ occurring in the exhaust manifold. Excessive EGTs can lead to serious issues, such as turbo damage, piston damage, manifold and cylinder head cracking, and failed exhaust valves. In short – not great for your vehicle or your bank account. So how does a quality aftermarket exhaust reduce these EGTs?
One of the key roles of an exhaust is to remove heat from the exhaust manifold by extracting the hot gases to the rear of the vehicle. Here’s where an unrestricted mandrel bent pipe will improve the scavenging effect and gets these gases flowing through the system as quickly as possible. This means less heat building up near the engine and exhaust manifold and as a result- lower EGTs.
All Torqit exhausts are entirely mandrel bent, and pre-DPF systems also include a titanium-coated dump pipe. This titanium coating has extremely high heat resistance, and by containing the heat so it can travel further away from the engine before it disperses, it keeps your engine bay cooler and protects the engine and its components. This increases the performance of the exhaust, extends its lifespan, and let’s admit it- looks pretty neat too.
It’s worth noting that heat-related damage can occur before becoming obvious to the driver, which is why Torqit also add an EGT gauge (or pyrometer fitting) on all our pre-DPF systems. You can see exactly what’s going on with your 4WD for total peace of mind.
7. Does an aftermarket exhaust improve fuel economy?
When exhausts are called a ‘performance upgrade’, it’s easy to be sceptical at how something that improves power and torque could also save fuel. However, by replacing a restrictive stock system, an aftermarket exhaust will potentially improve your fuel economy. Add a high-flow exhaust, and your engine will work more efficiently with less effort. This means your vehicle uses less fuel to achieve the same, if not better, performance than previously.
Driving habits like gentle acceleration and cruising at a constant speed can also go a long way. However, if fuel savings are your main priority, you will see the biggest difference by adding a couple of other mods along with your exhaust, such as a throttle controller or engine chip.
At the end of the day, your fuel consumption will depend on how you drive, although it’s worth noting many who have installed a Torqit exhaust have reported an improvement in fuel economy. Interestingly, that’s even with the vehicle under load, like this customer who tows a 3500kg van…
“I had my 3.5” exhaust fitted…achieved exactly 3 litres per hundred better fuel economy… the engine is definitely breathing better, I can notice a fair bit less pedal required at highway speed (105 to 110km)” – A. Darby
8. Why exhaust systems must come with a catalytic converter or a DPF
If you’re running a pre-DPF/ turbo back exhaust, legally, your vehicle requires a catalytic converter. Cats reduce your vehicle emissions by converting them into less harmful substances, but the downside with factory cats is they tend to be overly restrictive.
The good news is a quality high-flow cat can still meet emission standards without reducing your rig’s performance. Case in point – Torqit’s high-flow catalytic converters have 200 CPSI (cells per square inch) compared to the 400 CPSI of a factory cat. This means Torqit’s cats:
- Increase exhaust flow
- Improve power, fuel economy and overall performance
- Enhance exhaust sound while removing harshness from the note
- Reduce soot and smell
- Keep the back of your rig clean
Aside from being illegal, removing a catalytic converter provides no noticeable performance gains compared to a high-flow cat, and your 4WD will smell.
Torqit Single Exit 200 Series Landcruiser Exhaust, pre-DPF
Now on to diesel particulate filters (DPFs). Every modern diesel vehicle runs a DPF to reduce emissions; however, these are known for reducing performance. If you’re thinking of deleting your DPF, here are a few things to keep in mind:
- It is illegal to modify or remove your DPF
- Removing your DPF makes your vehicle un-roadworthy, voiding your insurance
- If you’re involved in an accident, you could be held accountable regardless of who is at fault
- If you need to provide a roadworthy certificate to sell your vehicle, you will have to reinstall the DPF and foot the bill
- A DPF delete requires sensors to be turned off through the ECU, voiding your vehicle warranty
With DPFs here to stay, the better alternative to a DPF delete is installing a DPF back exhaust. It’s a question we always hear- is a DPF Back exhaust still worth it? The answer is yes, and here’s why:
- Reduced EGTs: to improve your engine’s performance and lifespan.
- Better sound: a deeper, quality exhaust note.
- High durability: a quality DPF back exhaust like Torqit’s is far tougher than a factory system. If you’re heading off-road, rock crawling or driving through mud and water, the system will stay intact and in good condition.
To sum it up, keeping your exhaust system legal is a good idea if you’re looking to avoid fines and warranty issues.
9. Aftermarket Exhaust Fitment
Torqit’s exhaust range is also designed to bolt together for fast, easy fitment. This means most of our systems can be DIY installed from your driveway, with no hoist required. However, if you’d rather leave the job to someone else, Torqit’s huge dealer network is at your service.
For Shaun Whale from 4WD 24/7, the ease of fitment got a big tick of approval. Check out how easy it was to install Torqit’s DPF-Back system on his 200 Series cruiser…
Keen to see a pre-DPF system get installed? Check out this step-by-step guide to fitting Torqit’s 3.0L Hilux Exhaust.
Of course, there’s no point in buying a new exhaust if it’s not going to fit. Vehicle mods such as aftermarket fuel tanks, undertray toolboxes, suspension upgrades and chassis extensions must all be considered. To accommodate these where possible, Torqit has worked with a range of quality Aussie brands, including JMACX, Brown Davis & Long Ranger Australia, Norweld, Creative Conversions, DMW, TJM, and ARB.
10. Other recommended exhaust parts
After everything we’ve discussed, there are still a couple more things to look out for, including the quality of the flanges, brackets, and welds. Check out what Shauno from 4WD 24/7 has to say on each point…
TO WRAP IT UP…
In short, a quality performance exhaust will pay off big time in long-term performance and reliability.
Before you buy an exhaust, we recommend doing your due diligence on the manufacturing quality, the material used, the components, and all the other points discussed above. Lastly, remember an exhaust manufacturer with a well-made product is prepared to back it up with a decent warranty.
Take it from 4WD owners who have already made the upgrade – check out what they’re saying here.
Keen to see the exhaust options for your rig? Click here or reach out to us below for a quote.
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