Stone Exhaust BMW N55 F20 F21 F22 F23 F30 F31 F32 F33 F36 Catless Downpipes for M135i, M235i, 335i, 435i, X3 35i and X4 35i
Unlock serious performance and sound from your BMW N55 with the Stone Exhaust catless downpipe. This high flow decat downpipe is engineered for maximum exhaust gas velocity and minimum back pressure, delivering faster turbo spool, sharper throttle response and a harder hitting exhaust note. Perfect for those searching for BMW N55 downpipe, BMW N55 catless downpipe, BMW N55 decat, BMW M135i downpipe, M235i downpipe, F30 335i downpipe, F32 435i downpipe, F25 X3 35i downpipe and F26 X4 35i downpipe.
Designed using 3D scanning, reverse engineering and advanced flow velocity simulation, Stone Exhaust has created a one piece, precision bent downpipe that eliminates internal weld intrusion to keep the gas path ultra smooth. We have fitted these at Nforcd and our customers consistently praise the fitment quality, weld integrity and the transformation in sound and response.
Why choose the Stone Exhaust N55 catless downpipe
- Catless decat downpipe for BMW N55 turbo engines - M135i, M235i, 335i, 435i, X3 35i xDrive, X4 35i xDrive and X4 M40i xDrive
- One piece design with 7 axis CNC bending for exceptional roundness and flow
- Unique flex section helps absorb heat expansion and vibration to reduce stress and prevent cracking
- Crisscross and overlapping welds at the turbo flange for strength under extreme temperatures
- Machine welded by robotic arms for precise, clean penetration and consistent quality
- Developed with 3D scanning and CFD style simulation to optimise diameter, routing and bend angles
- 100% OEM fitment for a direct bolt on install
Engineered for maximum flow
Stone Exhaust utilises 3D scanning of OEM BMW N55 components to identify restrictions and tune pipe geometry. The result is an integrally moulded pipe that maintains an impressive 98% roundness through bends, with outer bore wear held to around 25% at 180°. Combined with machine perfect welds that avoid internal weld bead and ash, exhaust gas speed is preserved for rapid turbo response. Manufacturing accuracy is tightly controlled to an error under 0.025 mm.
Performance and sound
Reduce back pressure, improve turbo spool and let the N55 breathe. A catless downpipe is a proven upgrade for stage 2 tuning, offering a sharper, more aggressive exhaust tone with pronounced turbo character. Expect a deeper idle, crisper upshifts and a stronger mid range surge when paired with suitable ECU calibration. If you are searching for N55 stage 2 downpipe, N55 decat pipe or BMW F series downpipe upgrade, this is the premium choice.
Compatibility - BMW N55 petrol turbo
BMW 1 Series
- F20 M135i and M135i xDrive (2011+ and LCI 2015+)
- F21 M135i and M135i xDrive (2011+ and LCI 2015+)
BMW 2 Series
- F22 M235i and M235i xDrive (2012+)
- F23 M235i and M235i xDrive (2014+)
BMW 3 Series
- F30 and F31 335i and 335i xDrive (2011 to 2015)
BMW 4 Series
- F32 435i and 435i xDrive (2012+)
- F33 435i and 435i xDrive (2013+)
- F36 435i and 435i xDrive (2013+)
BMW X Series
- F25 X3 xDrive35i (2009 to 2017)
- F26 X4 xDrive35i (2013 to 2018) and X4 M40i xDrive (2014 to 2018)
Wastegate variants and part numbers
The BMW N55 was produced with two wastegate styles. Please select the correct downpipe for your car:
- PWG Pneumatic Wastegate - Part number A201P
- EWG Electronic Wastegate - Part number A202P
Not sure whether your N55 is PWG or EWG? Check the turbo actuator on your car - a vacuum line indicates PWG, an electronic plug indicates EWG. If you need help, contact us.
Manufacturing detail
- Reverse engineered with 3D scanning to map OEM fitment and eliminate weak points
- 7 axis CNC bending maintains pipe roundness and flow through tight radii
- Direct spot welding by mechanical arms for consistent, high strength joints
- Crisscross welding at high stress areas around the turbo flange
Fitting and ECU calibration
Professional installation is recommended. For hassle free fitting, book with Nforcd in Warwickshire - request a quote at Sales@nforcd.com. An ECU calibration is recommended after installing a catless downpipe to optimise performance and manage potential warning lights.
What our customers say
We have installed these Stone Exhaust N55 catless downpipes for multiple customers. Feedback has been overwhelmingly positive on OEM like fitment, build quality, welding finish and the addictive N55 sound and response once fitted and mapped.
Warranty and manufacturer
Manufactured by: Stone Exhaust
Warranty: Stone Exhaust 2 Year Warranty
Important information
Catless downpipes are intended for off road and motorsport use where permitted. Please check local regulations before purchase and installation.
Media
Stock vs Stone Exhaust catless downpipe
Fitted photos
BMW N55 F30 335i Stone Exhaust sound
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