Stone Exhaust BMW B48E F40 F44 Cat-Back Valvetronic Exhaust System for M135i xDrive and M235i xDrive
Transform the sound and performance of your BMW M135i xDrive F40 or BMW M235i xDrive F44 with the Stone Exhaust Valvetronic Cat-Back Exhaust System. Designed specifically for the BMW B48E engine platform, this premium cat-back exhaust delivers the distinctive Stone signature tone, genuine performance gains proven on Stone’s in-house dyno, and true OEM-level fitment thanks to meticulous 3D scanning and reverse engineering.
As a UK specialist in performance BMW exhaust systems, we’ve fitted and used these systems ourselves, and our customers consistently praise the sound quality, the valve control convenience, and the refined, drone-free cruising. If you want a BMW M135i exhaust or BMW M235i exhaust that is valved, plug and play and built to last, this Stone Exhaust cat-back is the upgrade you’ve been searching for.
Why choose this Stone Exhaust cat-back for your BMW M135i xDrive or M235i xDrive
- BMW B48E platform specific design for F40 M135i xDrive and F44 M235i xDrive
- Valvetronic dual-valve technology with remote control for ON, OFF and AUTO modes
- Plug and play OBDII controller for quick installation and valve control
- Eliminates drone often found on the factory system for refined motorway driving
- One piece design with precise machine welding for strength and durability
- 3D scanning and reverse engineering for 100% OEM-style fitment
- Dyno developed in house by Stone Exhaust for proven performance improvements
Valvetronic control you can feel and hear
The Stone Valvetronic system includes a dedicated remote offering three modes: ON, OFF and AUTO. Open the valves for a deeper, sportier note and maximum flow, close them for a quieter, commuter-friendly drive, or use AUTO to trigger the valves at a predefined RPM. The system uses a plug and play OBDII controller for simple set-up and reliable operation.
Engineered for performance and precision
- Seven-axis CNC bending achieves up to 98% roundness and precise routing to optimise flow
- Crisscross and overlapping welding techniques increase penetration and durability at high-heat joints
- Direct spot welding via mechanical arms for consistent, high-strength welds
- Integrally moulded pipework with accuracy to within 0.025 mm
OPF solution available
Running an OPF-equipped car? Stone offers an OPF delete solution that can be included free of charge. This allows you to install the Stone cat-back on OPF cars without triggering error codes, avoiding the need to code out OPF on the ECU. Simply request the OPF delete option when ordering.
Often purchased together
Many owners pair this cat-back with the Stone Exhaust BMW B48E F40 M135i xDrive Catless Downpipe or the Stone Exhaust BMW B48E F40 M135i xDrive Eddy Catalytic Downpipe for an even more engaging sound and enhanced flow.
Compatibility
Engine: BMW B48E
- BMW 1 Series F40 M135i xDrive 2018+
- BMW 2 Series F44 M235i xDrive 2018+
Part numbers
- AP548AS - F40 M135i xDrive
- AP548BS - F44 M235i xDrive
What you’ll love
- Sporty, refined tone with valves open and quiet, comfortable cruising with valves closed
- Noticeable performance improvement backed by Stone’s in-house dyno development
- OEM-style fitment and quality thanks to 3D scanning, reverse engineering and machine welding
- Reliable plug and play OBDII control with simple install and instant valve operation
Warranty
Stone Exhaust 2 Year Warranty.
Photos and videos
Stone Valvetronic System Installation
BMW B48E F40 M135i xDrive - Stone Catless Downpipe + Valvetronic Cat-back Sound
Professional fitting
Want it fitted by experts who know these cars and systems inside out? Nforcd offers professional installation in Warwickshire. Request a tailored fitting quote at Sales@nforcd.com.
Popular search terms
BMW M135i exhaust, BMW M235i exhaust, BMW F40 M135i xDrive exhaust, BMW F44 M235i xDrive exhaust, BMW B48E exhaust, BMW B48 performance exhaust, M135i cat-back, M235i cat-back, BMW M135i valved exhaust, BMW M235i valved exhaust, valvetronic exhaust BMW, valve controlled exhaust BMW, plug and play OBD exhaust controller, OPF delete solution BMW, Stone Exhaust UK, Stone Exhaust M135i, Stone Exhaust M235i, cat-back exhaust system UK, performance exhaust BMW 1 Series, performance exhaust BMW 2 Series, best exhaust for M135i, best exhaust for M235i.
Image gallery
