Top 5 customers’ exhaust Q&As

Bosal Automotive & Industrial Components, one of the world’s leading suppliers of complete exhaust systems, shares its expertise to address the most common exhaust questions asked by customers.

There seems to be a hole in the bottom of the inlet endplate on the rear box. Is this a manufacturing error or is it supposed to be there?

This will be the drain hole; it is designed to release the condensate and increase the life of the product. So successful was this innovation that Bosal received an Environmental Technology Innovation Award, and the concept has been adopted by several vehicle manufacturers for their OE product.

I’ve previously bought cheaper brands of exhausts and they sounded noisy. How does the sound compare with a Bosal exhaust?

Type Approval guarantees that the aftermarket replacement part is equal to the vehicle manufacturer’s original equipment specifications. Bosal is committed to developing Type-Approved products that contribute to sustaining the environment through lower noise levels, optimised back pressure and improved emission levels. From manifold flange to tailpipe, we constantly aim for the highest possible standards and strive to implement OE technology to our aftermarket products.

Europe is years ahead of the UK in terms of environmental awareness. In most European countries, it is illegal to fit an exhaust system that does not carry Type Approval, making the UK a dumping ground for non-approved cheap imports.

As a benefit to the environment, the specifications of a Type-Approved exhaust ensure the engine is working within the correct air fuel ratio, providing maximum power whilst maintaining the least fuel consumption, ensuring cleaner emissions, lower noise levels and improved fuel economy.

Type Approval is a major point of differentiation for Bosal products. It also offers your customers a genuine opportunity to make a statement of environmental responsibility by choosing to fit Type-Approved.

Some exhaust companies cross reference their part numbers to Bosal part numbers which can lead to problems, as not every exhaust company is the same in the way they approach Type Approval. For example, one company may use the worst-case scenario and test for the largest engine, then cascade the design over the lesser engine sizes for both petrol and diesel.

Bosal would Type-Approve to both engine size and fuel type individually, ensuring a better result for your vehicle rather than a ‘one size fits all’, as each has different noise and back pressure requirements. One Bosal number may cross reference to many competitor numbers and choosing the wrong one because they look physically similar could cause problems or delays for your customer.

Bosal would prefer to find the correct Bosal part for you. We would just need the registration number of the vehicle, as with newer vehicle models there are many chassis codes, engine codes and horse powers to consider. This means you get it right first time with Bosal!

Do you have a gasket for this part?

Even better; we have a fitting kit. For quality and warranty, we always recommend that you purchase new fittings compatible with the replacement part when replacing any exhaust piece. Sourcing mounting parts from the manufacturer that designs and makes the exhaust system is the only way to guarantee the perfect fit. That’s why whilst developing the exhaust system, Bosal also develops the installation hardware to the same exacting standards. Most Bosal parts now have a fitting kit associated to them. Adding this list of kits to your purchasing system can make a big difference to your sales revenue.

We have been known to fit cats to a vehicle only for the customer to return a week later with a problem. Why is this?

When you fit a new cat, please make sure that you get a copy of the emissions report before the new cat is fitted and another copy after the cat is fitted. The results are useful if the customer ever comes back with a problem. There are things in the results that may help you find the issues, even with a pass set of results.


To use an example, lambda sensors are useful for fault finding if the pass results are 1.019 to 1.030, which tells us that there is an excess of oxygen being measured at the tailpipe (running lean) even though technically it’s a pass. This could mean there’s a slight air leak in the system. Check gaskets, seals, flexi parts and joints for damage or ill-fitting etc. The desired result for lambda should be 1.0.

Equally, if the result is low – 0.098 – or lower, this means there’s an excess of fuel (running rich). This will be accompanied by an elevation in CO and HC measured at the tailpipe. Start by checking the basics such as spark plugs, coil packs, leads, sensors etc.

Remember, a new cat will be working hard and will mask small faults. It will hide the problem at the expense of its lifespan. If the results are higher than the maximums for the MOT test, then there is a problem before the cat every time. Remember that a cat cannot increase emissions – only reduce them!


Are your cats Type-Approved?

This is easy to check; any cat part number beginning with 099 or 090 is Fully Type-Approved and comes with a full fitting kit. We even have a Blue Angel certified range of cats that are made of eco-friendly materials and are tested to very high TUV standards.

Our Type-Approved DPF range can be identified by the part numbers beginning with 095 and 097.

For vehicles registered on or before 1st March 2001, the cat does not need to be Type-Approved and Bosal has a range of cats for these vehicles. These can be identified by starting with the number 098.

It’s important to remember that you could be liable to a £5,000 fine for supplying a none-approved cat for a vehicle registered on or after 1st March 2001. Spot checks will be carried out by the Vehicle Certification Agency, with fines up to £5,000 for non-compliance.



For more information, interviews or images please contact:

Claire Brown or Kimberley Hornby, Hornby Whitefoot PR

Tel: 07787 505963

Tel: 01858 681122         E-mail:



About Bosal Automotive & Industrial Components Ltd

BAIC Ltd was created in 2013 as the wholly owned Sales and Distribution arm of Bosal Group in the UK. Bosal Group was established in 1923 in Alkmaar, Netherlands. The annual turnover in 2014 was in excess of € 714 million. The Bosal Group employs over 4.900 people in 34 manufacturing plants and 18 distribution centres. Bosal´s customer base includes all major car manufacturers worldwide as well as a variety of leading industrial conglomerates.

Bosal has been trading in the UK since 1977, from the same site in Preston, Lancashire. BAIC Ltd stock an extensive range of Bosal manufactured Emission Control Systems including Silencers, Pipes, Catalytic Converters and Diesel Particulate Filters. Additionally, BAIC Ltd also stock a wide range of Towbars – Flange, Swan Neck and Detachable – as well as Electric Sets and Accessories, Cycle Carriers and Roofbars.

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