Before & After ECU Remap Dyno Results

Before & After ECU Remap Dyno Results – Proven Power Gains

Tuning Gain Calculator

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

    
 
 
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   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
  
 
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   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.
  
 
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   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 👍🏻
  
 
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   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.
  
 
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   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
  
 
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   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.
  
 
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   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.
  
 
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   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😎🙏🏼
  
 
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   Aurimas Gercas 
 
 
 
 Trustindex verifies that the original source of the review is Google. Great service, recommend.

Proven Dyno Power Gains with ECU Remapping in Slough

Don’t just feel the difference — see it on the dyno graph. Book your Slough-based ECU remap today and receive before-and-after rolling road results that prove the gains.

5-Star Google Reviews

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Years of Experience

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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 a before-and-after dyno result?

It’s a comparison of your car’s power and torque on our rolling road before the remap and after tuning.

Why should I have dyno-tested ECU remapping?

Dyno testing ensures your car is tuned under real-world load conditions, giving accurate, safe, and proven results.

Can I see exactly how much power my car has gained?

Yes — you’ll receive a dyno printout showing horsepower, torque, and power curves before and after remapping.

Is dyno tuning safe for my car?

Absolutely — our rolling road simulates real driving conditions in a controlled environment, making it safe and precise.

Do modified cars benefit from before-and-after dyno runs?

Yes — if your car has upgrades like a turbo, exhaust, or intake, dyno runs show exactly how much performance has improved.

Do you provide dyno-tested ECU remapping outside Slough?

Yes — while our rolling road is based in Slough, we welcome customers from across Berkshire and nationwide.

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