BMW M340i Stage 1 & Stage 2 Tuning

BMW M340i Stage 1 & Stage 2 Tuning – ECU Remap Specialists at Our Workshop

BMW M340i Stage 1 & Stage 2 Tuning

The BMW M340i, equipped with the latest generation B58 3.0-litre turbocharged straight-six engine, delivers an exceptional balance of refinement, performance, and everyday comfort. But with Stage 1 and Stage 2 ECU tuning, there’s still a huge amount of untapped potential waiting to be unleashed. At our Slough tuning workshop, we specialise in creating custom ECU remaps that transform the M340i into an even more exhilarating machine.

Our Stage 1 ECU remap is designed for stock or near-stock M340i models, delivering significant gains in horsepower and torque while enhancing throttle response and mid-range pull. This upgrade keeps full reliability and smooth drivability intact, making it ideal for both daily driving and spirited weekend use.

For those seeking maximum performance, our Stage 2 ECU tuning takes the M340i to another level. Combined with supporting modifications such as a high-flow downpipe, uprated intercooler, and performance intake, the Stage 2 setup allows the B58 engine to run cooler, breathe more efficiently, and deliver relentless power under sustained load – perfect for performance enthusiasts and track-day drivers.

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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.

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Book Your BMW M340i Stage 1 or Stage 2 ECU Remap in Slough

Unlock the hidden performance of your BMW M340i with our custom Stage 1 and Stage 2 ECU remapping services. Using advanced tuning software and dyno-proven methods, we deliver safe, reliable, and dramatic power gains. Book today and experience the true potential of your M340i.

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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 will Stage 1 add?

Stage 1 tuning typically delivers 50–80 bhp gains with a noticeable increase in torque and acceleration.

Is Stage 1 safe for my standard M340i?

Yes – our Stage 1 maps are designed to work with stock hardware while maintaining long-term reliability.

What hardware upgrades are needed for Stage 2?

Stage 2 requires performance upgrades such as a high-flow downpipe, intercooler, and induction kit.

Will my car still pass its MOT with Stage 2?

With a sports cat, yes. A decat may require reverting to stock for emissions testing.

Do you offer dyno testing?

Absolutely – we provide before and after dyno runs to show verified performance improvements.

Can tuning improve fuel economy?

Under light driving conditions, fuel efficiency can improve, but spirited driving will naturally use more fuel.

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