What makes a quality aftermarket exhaust?

When specifying a replacement aftermarket exhaust, ensuring that the vehicle’s efficiency, performance and MOT compliance are preserved is a primary concern. With this in mind, Doug Bentley, head of product development at UK aftermarket exhaust manufacturer Klarius, has issued a number of pointers about what makes a quality aftermarket exhaust.

Producing independently tested Type-Approved emissions products has always been a routine activity for Klarius. Type approval is the EU standard for conformance to OE specifications. Klarius is the only UK aftermarket exhaust manufacturer to produce aftermarket exhaust products to these strict standards, and have them certified. All emissions examinations are performed at a dedicated onsite test track facility. Klarius exports a large part of its production output to the EU and the company’s UK customers benefit from the same high standards.

The independent testing and type-approval process ensures all Klarius exhausts meet strict emissions, noise and backpressure levels. Fitting approved is clearly recommended, however not enough people even within the industry know that fitting a non-type approved product can have multiple impacts on the characteristics of a vehicle, including a significant reduction in power at the wheels, lower efficiency, higher emissions and a shorter life expectancy for the engine and other ancillary parts.

Choice of materials is vital in producing a quality exhaust. The corrosion protection offered by stainless steel is ideal, however, it has a number of characteristics that can make it unsuited for automotive exhaust applications. Primarily, it is expensive and brittle when welded in thin tube sections, hence the exhaust is often made from a heavier gauge than necessary, which adds weight.

Material weaknesses can be exacerbated by the continual vibrations generated by rough road surfaces and speed calming measures. The vibrations caused by say, a speed bump, can put huge stress on the weld between box and pipe. With a brittle and hard material, this weld can become a weak point on the exhaust, causing failure. To combat this Klarius uses a custom grade of aluminised steel, providing both durability and versatility due to a more malleable ferrous steel core and a corrosion resistant aluminium exterior.

With regards to welding, Klarius employs a specially developed material solution that creates a strong corrosion resistant bond. The same attention is given to fitting equipment, which is designed for each exhaust model in durable materials. By specifying quality materials throughout it is possible to ensure products withstand the real demands of the road.

The specification of high grade materials also helps efficiency. A constriction in the exhaust pipe will increase back pressure in the system as gas is compressed slightly as it exits the exhaust. Over time this can damage the engine and reduce the performance of the car. Quality manufacturers will usually employ high grade pipe materials and bending techniques – which produce a more consistent diameter throughout the exhaust bend. This also apples to internal baffles and noise reduction packing, which applied correctly ensure that no efficiency penalties are encountered with an exhaust that has correct back pressure.

Testing is a crucial aspect of manufacturing a quality exhaust and this takes two forms; one for fit and the other for operational performance. For example, Klarius offers a ‘Fit First Time’ guarantee for all its emissions products. To achieve this, it tests every exhaust designs on actual vehicles of the correct make, model and production year.

Car manufacturers have a habit of changing the specification of vehicles towards the end of the design and development process, or soon after production starts. These changes have to be taken into account. Therefore, even if the OE part number appears to be the same for different models, a physical check is still essential.
What makes a quality aftermarket exhaust?

There is nothing more frustrating for a garage technician than making alterations to a supplied part in order to make it fit. It will inevitably take time (which is money) to remedy and often ends up compromising the integrity of the part, affecting long-term service life or in extreme cases, actual performance. For a quality exhaust, the fit has to be excellent.

Lower quality exhausts can have a grave effect on the performance of a car. The main concern is back pressure, as too much can strangle the engine, while too little can cause it to wheeze as it has nothing to push against. A poorly fitted or designed exhaust may not pass an MOT emissions and noise test either, and it will be lowering fuel efficiency, engine power and affecting noise levels throughout the lifetime of the car. Testing is absolutely crucial here and is the only way of ensuring an aftermarket design meets OE specifications.

Klarius bench tests for back pressure and uses its own test track with acoustically calibrated tarmac behind the factory to test noise levels.

To ensure you specify a quality replacement exhaust, it is worth remembering that:
• A fully Type-Approved exhaust performs to the most exacting standards, preserving a cars performance to OE standards or higher
• Higher grade materials increase the durability and efficiency of the exhaust, especially associated welds
• Correct fitting is vital to preserve efficiency, (always choose a fitting kit with a replacement exhaust)
• Tested products operate at a guaranteed performance level
• Poor quality exhausts may not pass an MOT test, and can adversely affect a car in the long and short term
• A poorly designed exhaust can greatly affect levels of back pressure, and therefore engine performance
• Premium quality aftermarket exhausts are available at a standard price, but be careful who you specify as they are not all created equal.

Bentley also comments that all 10,000+ products in the Klarius Emissions Control Range are available for purchase by distributors, stockists and resellers with next morning delivery in the UK as standard.