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BMW M135i F20/F21 ECU Remapping

BMW M135i F20/F213.0 N55 · 2012–2015

Stage 1 £499

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4.9/5500+ Google ReviewsSee Google Reviews

The BMW M135i F20/F21 (2012 to 2015) leaves the factory with 320 PS and 450 Nm from its 3.0 petrol engine. Our Stage 1 estimate takes it to 390 PS and 550 Nm, roughly 22% more power and 22% more torque.

Stage 1 price

£499

Stage 1 ECU remap

Estimated gain

+70 PS · +100 Nm

Power

Stock
320 PS
Stage 1
390 PS

Torque

Stock
450 Nm
Stage 1
550 Nm

Figures are STX Tuning estimates for a healthy standard car, not a dyno result for your vehicle. Power is shown in PS. These are existing vehicle library estimates, not independently measured results.

Where would you like it done?
01753 439130
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More BMW tuning

1 Series F20/F21

118i 1.6 Petrol

135i E82/E88

135i 3.0 Petrol

1M Coupe E82

1M Coupe 3.0 Petrol

3 Series G20/G21

320d 2.0 Diesel

3 Series F30/F31

320d 2.0 Diesel

3 Series F30/F31

330i 2.0 Petrol

330d E90/E91/E92

330d 3.0 Diesel

330d F30/F31

330d 3.0 Diesel

What we do

More than just ECU remapping.

From Stage 1 and Stage 2 ECU remapping to gearbox tuning and supporting performance upgrades, STX Tuning offers specialist vehicle software and tuning services for compatible petrol and diesel cars and vans.

Explore the available options for your exact vehicle at our Slough workshop, with suitable mobile ECU remapping appointments available across selected surrounding areas.

Not sure which tuning service you need?

Tell us what you drive and what you'd like to achieve. We'll check your vehicle and help you explore the available options.

4.9/5 | 500+ Google Reviews
Get my tuning quoteCall STX Tuning: 01753 439130

Get Your M135i F20/F21 Quote

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  • Slough workshop
  • Vehicle-specific quotes

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Google Customer Reviews

What BMW Owners Say

See what customers say about their experience with STX Tuning.

Google Reviews

4.9

535 Google Reviews

  • Jake Bickmore

    Dec 2025

    STX Tuning were absolutely brilliant. The service was super fast — same day turnaround — and they solved an issue with my car that a main dealer claimed would cost me thousands to fix. It turned out the expensive repair wasn’t even necessary, and STX handled it quickly and professionally. Honest, efficient, and highly recommended!

    Posted on Google · view on our Google profile

  • Matthew Mooney

    Nov 2025

    STX were great! (its within ONYX which confused me when I got there, no biggy, just for anyone else reading it). I happened to be arriving when a guy must have been starting their shift, super helpful and got me to the right person. On the way in they even took the time to show my son the Lambo they had, this type of service is so nice to receive. The young guy we spotted fitting the wheels later on, thank you! In for a Stage 1 remap, all done in 30 minutes, and car drives brilliantly and exceeded expectations. Also at a great price as well. All staff I met were super nice and helpful. Credit to you guys! I will definitely be choose these guys going forward! Highly recommend.

    Posted on Google · view on our Google profile

  • Loizos Kyriacou

    Jun 2025

    Went to remap my GLE 250d and the whole process was smooth from start to finish. Super responsive, and had the job done quickly with zero hassle. The results are brilliant , noticeable power gains straight away and smoother drive overall. Would highly recommend them to anyone looking for a quality remap with excellent customer service!

    Posted on Google · view on our Google profile

  • Debby Cunliffe

    Jun 2025

    Fantastic service. Came to my home on a Sunday to remap my car. Great job done and lifetime warranty plus interest free payment facility over 4 months available. Highly recommend

    Posted on Google · view on our Google profile
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