performance exhaust systems custom exhausts

Performance Exhaust Systems and Custom Exhausts

What is an exhaust? What is an exhausts function?

An exhaust system, in a nutshell, is a component that carries exhaust fumes produced by the engine away from the car to be expelled into the air.  The engine burns fuel (petrol/diesel) and from this these waste gases are created.  In the same way a log fire burns fuel and has a chimney to channel and remove waste gases, a vehicles exhaust pipe channels and removes exhaust waste gases from a car’s engine.

The shape and thickness of a vehicles exhaust will depend on its engine size and the vehicles function.  Modern exhausts will have a component like a catalytic converter or sometimes a DPF (Diesel Particulate Filter) ,which are installed at a point along the exhaust pipe, to reduce emissions (amount of harmful waste gases).  This is done to meet government regulation. Another function of an exhaust is to keep the noise created by the engine down.  The level of noise a car’s exhaust makes form the factory is also influenced by regulation and the fact is most driver on the road do not want a growling exhaust drawing attention to themselves.

What is a Performance Exhaust? What is a Custom Exhaust?

A performance exhaust, probably stating the obvious, is an exhaust system that is designed to help the performance of the car.  Car’s will leave the factory with an exhaust that ensures the vehicle meets regulation standards of noise and emission alongside designed power standards for that model.  The exhaust system shape, diameter, and emissions controlling components (DPF/Catalytic Converters) installed will be in place to meet these regulations only.  “Performance exhausts”  or “Custom Exhausts” will be designed in a way that the main focus of its design is to optimise how the car performs.  This will be specific to the vehicle and the setup it has.

The main focus: “Airflow”

Channelling waste gases away from the engine is not for convenience only. The exhaust has to effectively and efficiently channel these gases away so that the engine can keep burning more fuel, applying power to the wheels.  If an exhaust cannot keep up with the rate at which the engine operates it can hinder performance by reducing power.

“Airflow” refers to the ability for fresh air to be drawn/forced into the engine and exhaust gases to be channelled away. Performance exhaust systems will be a specific width/shape to match the engine’s power output capability.  A more powerful engine will need a suitable performance exhaust to prevent engine power being limited when it applies it’s power to the wheels.  Interestingly many vehicle leave the factory with an exhaust that is limiting the power output of the engine it has.  A simple exhaust upgrade can remove this limiting factor and make a drastic difference to the vehicle’s overall performance.


What is a DPF (Diesel Particulate Filter)?

A DPF (Diesel Particulate Filter) is a component that is installed at a point along the exhaust system that removes harmful exhaust gases.  All the exhaust gases will pass through to be filtered before being expelled.  The reduction of harmful waste gases is required to meet government regulations.

What is a Catalytic Converter?

In the same way a DPF filters harmful exhaust gases that the engine produces so does a Catalytic Converter.  Some vehicles will have both a DPF and Catalytic Converter.

What is a GPF (Gasoline Particulate Filter)?

A GPF (Gasoline Particulate Filter) is a similar component to a DPF (Diesel Particulate Filter).  Both are positioned at a point in the exhaust system so that exhaust gases pass through and both filter out harmful gases before they reach the environment. It may be obvious but a GPF is found on exhaust systems of Gasoline (petrol) fuelled vehicles and a DPF on Diesel Fuelled.  Either type of vehicle may also have a catalytic converter providing additional filtering of harmful exhaust gases.

Is removing a DPF (Diesel Particulate Filter) illegal? Is removing a GPF or Catalytic converter Illegal?

Removing the DPF (Diesel Particulate Filter), GPF, or Catalytic Converter is not an illegal act but removing the DPF from a car and driving without it is illegal.

How does removing a DPF (Diesel Particulate Filter) help performance?

As we mention above its key to mention driving a car on the road without a DPF (or GPF, Catalytic converter etc) removed is illegal and is not something we recommend.  This being said it is still performed by many car owners.  The way in which doing this can potentially improve performance of a vehicle is by improving the flow of exhaust gases through the exhaust system.  When an exhaust system has a DPF installed the gases have to pass through it to be filtered before it can continue through the exhaust pipe before it is expelled.  This causes resistance and reduces “airflow”.  A good comparison would be when water is run from a tap with no resistance and then you place a sponge in the flow, the time in which it takes the water to reach the sink based is slowed down. A DPF acts in the same way to exhaust gas that the sponge does to water, the exhaust gases have to travel through it before they are expelled and are slowed down.  If you read our explanation above about “airflow” we explain how an exhaust must be able to efficiently remove gases from an engine.  We explain that if the exhausts ability to do this doesn’t match the engines output of burning fuel to produce these gases, the power the engine applies to the wheels can be limited.  So finally removing a DPF from the exhaust system allows the exhaust gas to pass through to the outside without being filtered. This can increase the power of the vehicle if the DPF resisting the exhaust gas removal was a limiting factor.  We MUST mention that driving a vehicle without a DPF or other emissions reducing components (catalytic converters, GPF etc.) is illegal and causes more harmful gases to reach the environment

How Performance Exhausts help and why upgrade your exhaust?

An exhaust that helps your car get the exhaust gasses out of the engine as quickly as possible can help your car generate more power.  The faster the exhaust gases leave the engine the faster fresh air can enter into the engine leading to increase power.   This is where performance exhausts come into play.  An exhaust that is better flowing throughout rev ranges improves the power output of the vehicle.  Performance exhausts will be designed to maximise this flow. Diameter of the performance exhaust, as well as its shape and lay-out, will all be designed to optimise flow and therefore power output. Exhaust systems can be replaced with full performance exhaust systems however some choose to replace the most restrictive parts of the exhaust system such as the downpipes or replacing components such as the catalytic converter.  When a performance exhaust is fitted ideally the cars ECU software has to be tested or upgraded to maximise engine operation to match the new upgraded exhaust component. At Cooksport we utilise our rolling road dyno to do just this.


What types of performance exhausts are there?

You may have come across a number of “Types” or descriptions of performance exhausts.  Here are some that you may have discovered:


Performance Exhaust Type What are they?
Performance Exhaust Downpipe A downpipe is not a complete exhaust but the section that connects the manifold to the catalytic converter. Changing the exhaust downpipe on a non-turbo car doesn’t really add much of a power increase. However when it comes to forced induction (Turbo/supercharger), the increased air being pumped into the engine requires an equally capable downpipe to carrying exhaust gasses away from the engine.  This is where a downpipe upgrade can help increase power output.  It’s important to note that a Turbo-back exhaust includes a downpipe when purchased so you would not need to purchase a separate downpipe.  If an upgraded downpipe flows into a unmatched ,thinner, lower performance part of exhaust system it will limit flow and power.


If you buy a turbo-back exhaust the downpipe will be included so there is no need to buy a downpipe separately.

Downpipes are sold separately for a number of reasons.  They will be sold as part of turbo kits so that they match the turbo output correctly.  Some may already have an exhaust upgrade and need just upgrade or replace the downpipe section so will purchase the separate downpipe.



Cat-back exhaust A performance exhaust system consisting of usually 1/2 to 2/3 of the total exhaust system.  Its is a performance upgrade replacing part of the original exhaust system. Usually from where the catalytic converter is located to the end of the exhaust. Essentially the middle of the pipework, rear pipework and tailpipe/tailpipes.  The component may include a silencer also.
DPF-back exhaust This type of performance exhaust is essentially the same as the above “Cat-back” but for diesel cars that have a DPF (Diesel Particulate Filter).  A DPF is a component that reduces emissions and is often fitted in a similar location to the catalytic converter.  A DPF-back performance exhaust replaces from the DPF to the end of the exaust.  Some cars may have both a DPF and a Catalytic converter so always check which performance exhaust is right for your vehicle.
GPF-back exhaust A GPF is a “Gasoline Particulate Filter”.  This is fitted to some petrol vehicles that were produced more recently.  A GPF-back exhaust is essentially the same type of performance exhaust upgrade petrol vehicles as the two mentioned above. The GPF-back will usually replace everything on the original exhaust from this emission reducing component (GPF) to the end of the exhaust.
Turbo -Back exhaust This performance exhaust replaces the exhaust system from the turbo all the way back to the tailpipes.  This includes the catalytic converter.  The road legal way includes this performance exhaust having an upgraded sports catalyst. The other non-road legal option is leaving the catalytic converter out and installing a straight through pipe. Newer sports catalysts are very advanced meaning both options offer similar power upgrades.  Note although most cars require a remap of the ECU and assessment on a dyno its is key that installing a Turbo-back involves a remap. If this is not done the sensors will detect as if the standard exhaust is still in attached and usually produce a warning that there is a serious engine issue.  Basically a remap of the ECU is required to allow the engine to know how to utilise the new component and produce the power that the new
Resonated performance exhaust A resonator is a type of silencer for an exhaust.  When buying an exhaust its common for it to have option of “resonated” or “non resonated”.  This is basically with or without a silencer (resonator).  Many will offer differing types of resonator.  Which you choose will depend on your own personal preference.  Some will allow a quieter sound when operating in lower rev ranges but then much louder when pushing the car more.  Some are as quiet as possible in both scenarios.  You may choose to have the exhaust as loud as possible and an example of this would be to have a straight cut non resonated exhaust.  Everyone has their own preference.
Non-Resonated performance exhaust As above.  A non-resonated exhaust is one without a silencer (resonator).  This often means there is nothing controlling the sound output so will be fairly loud throughout all rev ranges .


What is the best exhaust for power gain? What does a bigger/wider exhaust do?

The best exhaust for power gain is one that provides the best flow of exhaust gases away from the engine. This must match the engines capability to produce exhaust gasses from burning its fuel.  This is a simplification but essentially an exhaust wide enough and with the least resistance to channel exhaust gasses away from the engine. A wider exhaust allows for better exhaust gas flow in comparison to a narrow width exhaust that will limit power production from the engine.  It will also make the car louder.  An exhaust that is too narrow will limit exhaust gas removal which prevents fresh air entering the engine.  Its important to note that an exhaust can be too wide and cause power loss by not effectively channelling the gasses away from the engine. Performance exhausts are designed for specific vehicle models but also to be matched to certain power outputs of the engine.  An example would be if a car has a turbo upgrade, the exhaust needs to be matched to the exhaust gasses that the upgraded turbo causes the engine to produce.

Milltek Exhausts

Founded 1983 Milltek is a well know performance exhaust manufacturer.  They have a large distributor network allowing customers access their specialist products worldwide.  They are innovative in development and are immersed in the motorsport industry and have developed vehicles and exhaust systems for a number of championships.  These have included series such as BTCC and Volkswagen Cup.  This recently has advanced to Milltek becoming technical partners for Power Maxed Racing and BMR in the BTCC giving them a finger on the pulse of the ever changing motorsport industry.  This allows continuing, up to date, understanding of the requirements of the industry but also front line access to new breakthroughs.  This they then injected into development of their products allowing their customers access to this knowledge both on road and track.

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Scorpion Exhausts

Scorpion Exhausts are hugely popular.  Handcrafted in England, their unique performance exhaust designs and production quality are well known, as is their sound.  Scorpion exhausts are heavily involved in motorsport from Touring Cars all the way through to performance motorcycles.  They have even branched into performance scooters like the Vespa 300 GTS! The motorsport integration that Scorpion exhausts have has allowed years of development to create products that operate at the highest level of motorsport but at the same time bringing that same level of technology and knowledge to drivers on the road.  Scorpion Exhausts stay on the tip of the spear when it comes to developing new products. If a new performance model comes to market you can be confident they are in development or have already created an exhaust for this vehicle.  The Hyundai I30N was an example of this.  Scorpion Exhausts have developed a reputation for being a leader in the performance-exhaust space and customers can feel their passion and expertise in performance tuning being engrained into their products.

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Remus Exhausts

Remus exhausts produce performance exhausts for customers all around the globe.  They have three locations of production in Bosnia and Austria.  They were founded in 1990 and within a very short time were leaders in performance exhaust industry.  The majority of their production volume is actually exported from those locations to more than 60 countries in the world.  This alone demonstrates the reputation they have of producing popular and reliable products.  Constructing and maintaining this level of distribution of products to customers is not possible without these factors.  Remus exhausts are known for having an aggressive growl.  They have had parterships with AMG DTM and their motorsport experience clearly shows in the performance exhausts they produce.  A large number of brands actually have Remus Exhausts as the OEM (Original Equipment Manufacturer) on their car models.  These include BMW, Ducati, Aston Martin, Bentley, Mclaren, AMG and Porche to name a few

Cobra Sport

Cobra Sport, an incredibly popular performance exhaust specialist, is a family run busines that distributes their products to customers worldwide.  They have history in the UK performance exhaust market that spans over 50 years.  Their level of expertise and experience ensures Cobra Performance exhausts meet exact criteria and perfect fitment.  The Exhaust systems are all hand-made in Sheffield.  This combined with their long extensive heritage in the UK Performance space led to the company being awarded the internationally recognised “Made in Sheffield” Mark.

cobra sport exhausts made in sheffield

The Cobra Sport’s exhaust facilities in Sheffield have not only been developed over the years to make high quality products at a very efficient rate but also to still cater to individuals requesting design and production of one off requests for custom developments or projects.

They have wide experience in development of products on road and track.  Their clients include Subaru UK, Ginetta Cars and Isuzu UK to name a few.  They have been involved in the British Touring Car Championship developing exhausts in the heart of the motorsport and performance space. Their experience and knowledge once working with the BTCC quickly catapulted them to becoming technical partners to the AmD team and further into running two Honda Civic Type-R cars alongside Amd named “Cobra Sport AmD with AutoAid/RCIB Insurance racing.  This level of integration in motorsport but also the level of expertise to do so can only reflect the high standards of performance exhausts that they produce.

BTCC ford focus sponsored ford

Exhaust technical partners to AmD team hand crafting custom exhaust systems for NTGC-spec BTCC car. Partnered with AMD Tuning and purchased two Honda Civic type-r BTCC cars to run the BTCC team ‘Cobra Sport AmD with AutoAid/RCIB Insurance Racing.


Supersprint was started in 1955 and from this birth their goal has been to develop and build the highest standard of performance exhausts in the world.  This goal has been alive within the company ever since and has fuelled them to make their product development every-changing and innovative whilst maintaining the highest of quality.

They range of vehicles that Supersprint have develop and catered for is staggering. From Ferrari, Lamborghini, Porsche right down to tiniest of cars like the 54bhp Fiat Cinquecento Supersprint Supersprint’s wealth of knowledge and capability has been on show and appreciated.  They make products for luxury vehicles where not only appearance is key but lower sound requirements are requested without compromising power.  This is where they again shine in creating products with complex requirements and their history of development comes into play

Supersprint test each of their performance exhausts extensively.  They use a rolling road dyno and spend hours testing and adjusting their products until the required result is achieved.  Every year they carry out thousands of dyno/rolling road tests analysing a wide range of data. Most car models and engine variants will be tested by supersprint and actually provide a large number of the results to the public.

Supersprint are also invited/asked to provide behind the scene testing for top level racing teams.  Supersprint will offer their knowledge to help private and factory teams prepare for race events across the world where every aspect of setup needs to be correct and could be the difference between success of defeat. The trust these teams have in Supersprint reflects the type of product you get if you decide to use their performance exhausts.



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