When tuning and upgrading your car, the first consideration is improving airflow in and out of the engine. This means fitting beefier air intakes to force more cleansed air in for combustion, and an equally capable exhaust system to get rid of the spent gases faster. Both upgrades set the scene for more serious subsequent additions, such as faster spooling turbochargers or superchargers.
Why Upgrade Your Stock Exhaust?
Stock exhaust systems are designed without any future engine modifications in mind. They’re tailored to factory engine layouts and power output while meeting noise and pollution regulations. And they need to meet set price points. This combination of factors means most should last the vehicle’s lifetime, without major hiccups. Where they fail is when you’re harder on the acceleration pedal.
Most factory exhausts are made of crush-bent mild steel. This is adequate for normal driving conditions but will show its weakness the more speed the engine builds. The material can’t cope with high temperatures as engines near redlines, and the thinner walls can puncture due to higher pressure.
Another issue is low strength and the tendency for rusting and staining. Exposure to water and moisture is the main killer in factory tubing. However, some are known to puncture from road debris, or scrapping the car on bumps.
The biggest weakness though is the design. The narrow tubing and multiple restrictions along the length of the piping smother an engine’s potential to breathe. The numerous bends also create backpressure, or exhaust gases lingering in the piping and exerting pressure on various engine parts, including the outlet valves, cams and internals. As a result, the next combustion cycle is thwarted, meaning a loss of power.
Going Aftermarket
Going with aftermarket exhausts solves most (if not all) of the shortcomings in the factory unit. Layouts have been simplified to include straighter and wider tubing, material choices go for strength and durability, and production processes ensure that parts remain intact. This translates to a long list of benefits:
More Power and Torque
Tubing in aftermarket systems is at least half an inch wider. It also has fewer bends. This allows exhaust gases to escape faster, improving engine efficiency and setting the scene for subsequent combustion cycles. The layout relieves engines of damaging backpressure and increases horsepower and available torque. This is available across a wider power band, meaning better throttle response from the get-go, faster acceleration and lower fuel use.
Strength and Durability
Aftermarket systems swap mild for stainless steel and can feature exotic materials, including titanium, Inconel and carbon fibre if you’re willing to spend more. For a substantial increase in tensile strength, stainless steel is more than enough. The higher chromium content provides corrosion resistance, the presence of nickel and molybdenum (among other alloying metals) raises its melting point, and the heat treatment processes improve structural strength.
Better Sound
Sound profiles on aftermarket piping are appealing to the point that all other benefits are often overlooked. Performance systems have straight-tube mufflers to capture more of the engine sound, while still staying within noise limits and regulations. Systems can also include one or more resonators to fine-tune the exhaust note. And feature valving, or manually or automatically controlling a butterfly valve in the tips to increase or lower volumes. Most buyers go for a deeper, throatier sound, and in tune with any engine upgrades. Alternatively, you can opt for a ‘quiet’ exhaust to tame exhaust drone, and lower noise levels seeping into the cabin.
Customisation Options
Another advantage of aftermarket exhausts is the level of customisation. Modular designs allow buyers to mix and match parts to achieve set goals. Choose reworked headers and downpipe combos for increased exhaust scavenging (or the pulsating effect wider tubing has in drawing out more of the spent gases), revised catalytic converters to meet emissions targets, or high-flow cats to improve airflow. There’s also the option of improved dual-exhaust layouts in bigger displacement engines with X-pipe and H-pipe designs that reduce backpressure, and increase exhaust velocity and power output.
Manufacturers also tend to detail. Mounting hardware reduces vibrations (and resulting wear), while tips can be had in almost any shape, size or colour, and in single or twin configurations to up your vehicle’s appearance.
Weight Savings
Better materials mean weight savings, a bonus for racing or track use. Complete header or turbo-back systems can shed more than 20 kilos off when optioned in titanium or carbon-fibre parts. But even opting for stainless steel saves roughly 50 per cent compared to stock mild steel piping. And this without the high price.
Choosing an Aftermarket Exhaust for Your Car
Choose the exhaust that suits your budget, is compatible with the engine, and gets the results you want. Traditional choices are axle-back, cat and DPF-back, and header/turbo-back systems. All are priced differently and offer different performance and power gains. If you’re going for a complete engine or car rebuild, header back systems make more sense, as they’ll get more out of any mods you choose. If you’re after better throttle response, a raspier exhaust note and a bit more push, cat-back systems in petrol cars and DPF-back exhausts in diesels offer a good balance between price and performance. And when you’re looking for improved looks, more substance in the exhaust sound and something that will last in everyday driving, go for axle-back systems. There are savings when buying aftermarket exhausts online, with parts delivered to your specified address.