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Stone Exhaust

Stone Exhaust Eddy Catalytic Catted Downpipe for BMW N55 - F20 F21 F22 F23 F30 F31 F32 F33 F36 F25 F26 (M135i, M235i, 335i, 435i, X3 35i xDrive, X4 35i/40i xDrive) High Flow, Euro 6 MOT Friendly, PWG/EWG

Stone Exhaust Eddy Catalytic Catted Downpipe for BMW N55 - F20 F21 F22 F23 F30 F31 F32 F33 F36 F25 F26 (M135i, M235i, 335i, 435i, X3 35i xDrive, X4 35i/40i xDrive) High Flow, Euro 6 MOT Friendly, PWG/EWG

£1,401.60
£1,752.00 £1,401.60
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Wastegate

Heads-up on cancellations & returns: if you cancel an order or return an item, you won't get back 100% of what you paid. We apply a 10% restocking fee, the outbound shipping is non-refundable, and we have to pass on Shopify / PayPal payment processing fees; these aren't returned to us when we refund you. International orders also lose on exchange-rate spread in both directions. If the original packaging is damaged or missing, a reboxing charge applies. For international orders specifically, if you refuse to pay our shipping invoice or supply a prepaid label after placing the order, the same deductions apply. We're upfront about this — please be sure of your purchase before ordering.

Stone Exhaust Eddy Catalytic Sports Cat Front Pipe for BMW N55

F20 F21 M135i, F22 F23 M235i, F30 F31 335i, F32 F33 F36 435i, F25 X3 35i xDrive, F26 X4 35i and M40i xDrive

Unlock smoother spool, stronger midrange and a cleaner exhaust note with the Stone Exhaust Eddy Catalytic sport cat front pipe for the BMW N55 single turbo engine. This high flow catalytic converter upgrade is engineered for emissions-conscious performance, delivering rapid throttle response and impressive top end without nuisance warning lights. It is a direct bolt-on using premium SUS304 stainless steel, precision bends and OEM-style fitment points for hassle-free installation.

We have fitted this system in-house and the feedback from our customers has been outstanding. Fit is spot on, response is instant and the tone is refined with a purposeful growl under load. If you want a road-friendly catalyst upgrade that still lets your N55 breathe, this is the sweet spot.

Key reasons to choose this N55 catalyst upgrade

  • High flow sport catalytic converter designed for power and compliance
  • Patented Eddy Catalytic geometry promotes vortex mixing at low rpm for torque, then opens up for big flow at higher engine speeds
  • Optimised lambda probe placement for error-free running and no check engine lights
  • Immediate turbo spool and sharper throttle response
  • 3D scanned and CAD optimised for 100 percent factory-like fitment
  • SUS304 stainless steel throughout for corrosion resistance and strength
  • Dual cross-welding at the turbine flange for durability in extreme heat
  • Euro 6 compliant and UK MOT friendly
  • 76.2 mm diameter tubing for excellent gas flow

Engineering highlights

Each application is reverse engineered from the original parts using 3D scanning to lock in routing, diameter and bend geometry. Computational analysis refines gas velocity, heat zones and pressure distribution. Stone Exhaust manufacture on a 7-axis CNC bending platform to maintain roundness and precision, which reduces turbulence and avoids weld stress. Crisscross and overlapping weld techniques, plus direct spot welding, increase joint strength in areas that regularly see 800 to 1100 C.

Proven gains

  • Power increase: +24.4 PS at 5734 rpm
  • Torque increase: +16.6 ft lb at 2921 rpm

Vehicle compatibility

BMW 1 Series

  • F20 M135i and M135i xDrive 2011 to 2015
  • F20 LCI M135i and M135i xDrive 2015 to 2018
  • F21 M135i 2011 onward and M135i xDrive 2012 to 2015
  • F21 LCI M135i and M135i xDrive 2014 to 2016

BMW 2 Series

  • F22 M235i 2012 to 2016
  • F22 M235i xDrive 2013 to 2016
  • F23 M235i and M235i xDrive 2014 to 2016

BMW 3 Series

  • F30 F31 335i and 335i xDrive 2011 to 2015

BMW 4 Series

  • F32 F33 F36 435i and 435i xDrive 2012 to 2016

BMW X Models

  • F25 X3 35i xDrive 2009 to 2017
  • F26 X4 35i xDrive 2013 to 2018 and M40i xDrive 2014 to 2018

Part numbers

  • A201E - PWG
  • A202E - EWG

Please select the correct option for your wastegate type. If you are unsure whether your car is PWG or EWG, we will confirm before dispatch.

Free compatibility check

For peace of mind, provide your UK registration or the last 7 digits of your VIN at checkout and we will verify fitment prior to shipping.

Professional fitting

Installation and setup available at MJ Modifications in Warwickshire. Request a fitting quote or book by emailing info@mjmodifications.co.uk.

Manufacturer and warranty

Manufactured by Stone Exhaust with a 2 year Stone Exhaust warranty.

Ideal upgrade path

Pair with the Stone Exhaust M135i and M235i valved cat-back system for a complete N55 exhaust transformation.

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