Stone Exhaust Eddy Catalytic Downpipe for BMW N55
F20 F21 M135i, F22 F23 M235i, F30 F31 335i, F32 F33 F36 435i, F25 X3 35i, F26 X4 35i and 40i xDrive
The Stone Exhaust Eddy Catalytic Downpipe is the must‑have BMW N55 performance upgrade for road and track enthusiasts who want power, response and reliability while staying emissions conscious. This high quality catted downpipe for BMW N55 fits F20 F21 M135i, F22 F23 M235i, F30 F31 335i, F32 F33 F36 435i, plus F25 X3 35i and F26 X4 35i and 40i xDrive applications. Developed with patented eddy catalytic technology, it delivers stronger low‑rpm torque, rapid turbo spool and top‑end flow comparable to a very free‑flowing catalyst, with excellent emission control and no check engine lights.
We have installed this Stone Exhaust BMW N55 catted downpipe in‑house and customer feedback has been outstanding. Fitment is spot on, throttle response is immediate and the sound is refined with a purposeful note. If you are searching for BMW N55 downpipe, BMW M135i downpipe, BMW M235i downpipe, BMW 335i downpipe, BMW 435i downpipe, X3 35i downpipe or X4 40i downpipe, this is the premium, emissions‑friendly solution.
Why choose the Stone Exhaust Eddy Catalytic Downpipe
- BMW N55 high‑flow catalytic downpipe engineered for performance and compliance
- Patented eddy catalytic technology increases horsepower and torque versus conventional straight downpipes
- Vortex effect cleans exhaust gases at low rpm while maintaining crucial back pressure for torque
- Opens up at higher rpm for flow comparable to a very free‑flowing catalyst, with smooth top‑end power
- Real‑time O2 sensor placement designed to prevent check engine lights and deliver error‑free operation
- Immediate throttle response with no delay in power delivery
- Special 3D design for 100% OEM fitment with no modification required
- SUS304 premium grade stainless steel for strength and corrosion resistance
- Dual cross‑welding at the turbo flange for durability under extreme heat
- UK MOT friendly and Euro 6 compliant
- 76.2 mm diameter for optimised flow and spool
Engineering that sets it apart
Stone Exhaust reverse engineers each application using 3D scanning of OEM parts to identify the best routing, diameter and bend geometry. Computational simulation refines gas flow, heat zones and pressure distribution. Manufacturing uses a 7‑axis CNC bending machine to achieve industry‑leading roundness and precision, preventing flow disruption and weld stress. The result is an integrally moulded N55 downpipe with exceptional accuracy. Crisscross and overlapping welding techniques plus direct spot welding increase penetration and joint strength where temperatures can reach 800 to 1100°C.
Performance gains
- Power: +24.4 PS at 5734 rpm
- Torque: +16.6 ft lb at 2921 rpm
Compatibility – BMW N55 applications
BMW 1 Series
- F20 M135i and M135i xDrive 2011–2015
- F20 LCI M135i and M135i xDrive 2015–2018
- F21 M135i 2011+ and M135i xDrive 2012–2015
- F21 LCI M135i and M135i xDrive 2014–2016
BMW 2 Series
- F22 M235i 2012–2016
- F22 M235i xDrive 2013–2016
- F23 M235i and M235i xDrive 2014–2016
BMW 3 Series
- F30 F31 330e 335i and 335i xDrive 2011–2015
BMW 4 Series
- F32 F33 F36 435i and 435i xDrive 2012–2016
BMW X Series
- F25 X3 35i xDrive 2009–2017
- F26 X4 35i xDrive 2013–2018 and M40i xDrive 2014–2018
Part numbers
- A201E – PWG
- A202E – EWG
Please select the correct part number for your N55 variant. If you are unsure whether your BMW uses PWG or EWG, we will confirm for you before dispatch.
Compatibility check before dispatch
We run a free compatibility check to ensure perfect fitment. Provide your UK registration or the last 7 digits of your VIN at checkout and we will verify your N55 model and turbo type.
Fitting and support
Professional fitting is available at Nforcd in Warwickshire. Request a fitting quote or book an appointment by emailing Sales@nforcd.com.
Manufacturer and warranty
Manufactured by Stone Exhaust with a 2 year Stone Exhaust warranty.
Popular search terms
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Pair it with the Stone Exhaust M135i and M235i cat‑back valvetronic system for a complete BMW N55 exhaust upgrade.