Decat Downpipes and High-Flow Sports Cats Installation Specialists

Decat Downpipes and High-Flow Sports Cats Installation

Decat Downpipes Installation Specialists

Unlock the true performance of your car with our decat downpipe and high-flow sports cat installation service in Slough. Designed for sports cars, supercars, and performance vehicles, these upgrades improve exhaust flow, turbo spool, and horsepower, while delivering an unmistakable sportier exhaust note.

Whether you’re looking for the maximum power gains of a decat system or the road-legal benefits of a high-flow sports catalytic converter, our specialists provide professional installations tailored to your vehicle. With experience across BMW M, Audi RS, Mercedes AMG, Porsche, Ferrari, and Lamborghini models, we ensure every system is fitted to the highest standards.

Based in Slough, we are trusted by car enthusiasts across Berkshire, London, and nationwide who demand performance-focused upgrades, premium materials, and expert craftsmanship.

Why Choose Onyx Performance?

As Seen on Carwow

We’ve been proudly featured on Carwow – a testament to the quality, professionalism, and performance-focused results that set us apart. Watch our feature here to see us in action.

Expertise You Can Trust

With years of experience and deep technical knowledge, our team understands performance vehicles inside and out – from custom remaps to high-end servicing.

Advanced Workshop & Tools

We operate from a state-of-the-art facility in Slough, equipped with cutting-edge diagnostics, dyno testing, and industry-leading tools for accurate, high-quality work.

Tailored Solutions for Every Vehicle

We don’t believe in one-size-fits-all. Every car gets a bespoke approach, ensuring the best results whether it’s a remap, upgrade, or routine service.

Trusted Nationwide

Performance enthusiasts from across the UK come to Onyx because they know they’ll receive premium-quality workmanship, careful attention to detail, and honest advice.

Complete Care, All in One Place

From tuning and servicing to tyres, trackers, and immobilisers – we offer a full suite of services under one roof, all with a strong focus on safety, reliability, and top-tier customer support.

Customer Reviews

    
 
 
       Posted on Google  
   
   Mark Wiltshire 
 
 
 
 Trustindex verifies that the original source of the review is Google. Professional yet friendly, very helpful would recommend 👍
  
 
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   Paul Forrester 
 
 
 
 Trustindex verifies that the original source of the review is Google. Nice refurbishment of my alloys
  
 
      Posted on Google  
   
   Noel Kerins 
 
 
 
 Trustindex verifies that the original source of the review is Google. Excellent service, great quality job on 2 of my black alloys. They also did my father & husbands cars too. Great value for money and a special thanks to Ben.
  
 
      Posted on Google  
   
   Jamie Taylor 
 
 
 
 Trustindex verifies that the original source of the review is Google. Had my golf R mapped and tuned to stage 2 very impressed with the work they done Ben and Sam great guys very friendly and very professional would recommend 👍🏻
  
 
      Posted on Google  
   
   DSK 
 
 
 
 Trustindex verifies that the original source of the review is Google. Brought my Audi S3 in for a Stage 3 tune with a bigger turbo and full supporting mods. Things didn’t start smoothly — the Falcon turbo I had fitted from eBay turned out to be faulty and smoked heavily on the dyno.Instead of rushing the job or giving me attitude, they helped me swap it out for a proper Garrett PowerMax and carried on professionally. Then I ran into fueling problems caused by another low‑quality eBay part, and again they took their time, diagnosed the issue properly, fixed it, and made sure everything was right before continuing.After all the setbacks, they still mapped the car, spent a lot of time on it, and didn’t charge me anywhere near what the work was worth.They showed patience, honesty, and real skill. Very happy with the service and the way they looked after me.
  
 
      Posted on Google  
   
   randip 
 
 
 
 Trustindex verifies that the original source of the review is Google. Highly recommended. Fitted my catless downpipe and full exhaust on my Audi RS7. The sound is amazing!

The staff were very friendly and kept me updated at every step of the process
  
 
      Posted on Google  
   
   Dan Simmonds 
 
 
 
 Trustindex verifies that the original source of the review is Google. This is the second time I have used Onyx Performance first time for wheel refurbishment and last time for remap and i would use their services again in the future without a doubt. They are very knowledgeable about what they specialise in, they are polite and you can see they care not only about what their customers want to do but also about what they can offer the customer. Thanks to the OP team.
  
 
      Posted on Google  
   
   Taranjit Lehal 
 
 
 
 Trustindex verifies that the original source of the review is Google. Took my Mercedes C200 to Onyx performance for a stage 1 remap, my car is much quicker and throttle response is much better than before the remap. They also advise you about power and gains and the maps are tailored for your specific car and model, no stress on engine or gearbox. Thank Onyx , Brilliant work.
  
 
      Posted on Google  
   
   Carlos fernandez 
 
 
 
 Trustindex verifies that the original source of the review is Google. Absolutely fantastic service friendly customer service will definitely be going back for further modifications 5 star service do not go anywhere else other than onyx😎🙏🏼
  
 
      Posted on Google  
   
   Aurimas Gercas 
 
 
 
 Trustindex verifies that the original source of the review is Google. Great service, recommend.

Upgrade Your Exhaust Flow with Decat Downpipes or Sports Cats in Slough

Take your vehicle’s performance to the next level with our specialist exhaust upgrades. Whether it’s a track-focused decat system for maximum gains or a high-flow sports cat that balances performance with road legality, our team delivers precision fitting, expert advice, and proven results. Contact us today for a tailored consultation and competitive quote.

5-Star Google Reviews

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Why Choose Onyx Performance for Servicing?

Experts in Performance Cars

We know how to properly care for performance, modified, and luxury vehicles. Our team has the skills and experience to handle specialist requirements confidently.

Correct Service Schedules

Every service follows the exact schedule recommended by your vehicle’s manufacturer, helping maintain performance and protect your warranty.

Quality or OEM Parts

We only use high-quality aftermarket or original manufacturer parts, ensuring long-lasting reliability and top-level performance.

Full Vehicle Inspection

Our service goes beyond just changing oil. We inspect all key systems to keep your car safe, smooth, and road-ready.

Honest Advice, No Surprises

With transparent pricing and expert recommendations, you’ll always know what your car needs – no upselling, no hidden fees.

Fast, Trusted & Tracked

We offer quick turnaround, maintain service records, and send reminders – that’s why customers travel to us from across the UK.

Frequently Asked Questions

What is the difference between a decat downpipe and a high-flow sports cat?

A decat downpipe removes the catalytic converter completely for maximum exhaust flow and power gains, while a high-flow sports cat improves flow but retains a catalytic element, making it more suitable for road use.

Will a decat system increase my car’s performance?

Yes — a decat system provides maximum exhaust flow, improving turbo spool, throttle response, and horsepower output.

Are decat downpipes road legal in the UK?

No — decat systems are intended for off-road or track use only. For road legality, a high-flow sports cat is the recommended option.

Do high-flow sports cats still pass MOTs?

In most cases, yes. Sports cats are designed to be MOT-compliant, while still offering increased flow and performance.

Do you fit these upgrades on all performance cars?

Yes — we specialise in supercars, sports cars, and performance models including Audi RS, BMW M, AMG, Porsche, Ferrari, Lamborghini, and more.

How much does it cost to fit a decat or sports cat in Slough?

Costs depend on the vehicle model, part type, and installation complexity. Prices start from a few hundred pounds, with supercar systems quoted individually. Contact us for a personalised estimate.

Get a quick quote

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