BMW M3 / M4 Stage 1 & Stage 2 Tuning

BMW M3 / M4 Stage 1 & Stage 2 Tuning – Expert ECU Remapping at Our Workshop

BMW M3 / M4 Stage 1 & Stage 2 Tuning

The BMW M3 and M4 deliver an exceptional blend of precision engineering, everyday usability, and thrilling performance – but there’s still untapped potential within their S55 and S58 twin-turbo engines. At our Slough-based tuning workshop, we specialise in custom Stage 1 and Stage 2 ECU remapping to release this hidden power, transforming acceleration, responsiveness, and overall driving excitement.

Our Stage 1 ECU remap is ideal for stock cars, recalibrating boost pressure, fuel mapping, and ignition timing for safe yet impressive gains in both horsepower and torque. This upgrade maintains factory reliability while giving your M3 or M4 sharper throttle response and a noticeably stronger mid-range punch – perfect for both spirited road driving and track sessions.

For drivers wanting maximum performance, our Stage 2 tuning combines advanced ECU software with supporting hardware such as a high-flow downpipe, uprated intercooler, and performance intake system. This allows the engine to breathe and cool more efficiently, sustaining peak power during high-load conditions while delivering an even more aggressive driving experience.

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

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

Book Your BMW M3 / M4 Stage 1 or Stage 2 Remap in Slough

Unlock the full potential of your BMW M3 or M4 with our custom Stage 1 and Stage 2 ECU remapping. From subtle improvements in drivability to extreme performance transformations, our Slough tuning specialists deliver precision, reliability, and proven results. Book today and take your M Power driving experience to the next level.

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

How much power can Stage 1 add?

Stage 1 typically increases output by 60–100 bhp, with a strong torque boost for improved acceleration.

Is Stage 1 safe for a standard car?

Yes – it works perfectly with the stock engine and exhaust while keeping reliability intact.

What is needed for Stage 2?

Stage 2 requires hardware upgrades such as a performance downpipe, intercooler, and intake system.

Will my fuel economy change?

Fuel efficiency can improve during normal driving thanks to better engine efficiency, but it depends on driving style.

Do you provide dyno runs for proof of gains?

Absolutely – we offer before and after dyno testing so you can see exactly what’s been achieved.

Is Stage 2 suitable for track use?

Yes – our Stage 2 tuning is designed to withstand sustained high-performance driving.

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