Stone Exhaust BMW N20 F25 F26 Cat-Back Valvetronic Exhaust System - fits BMW X3 28i and BMW X4 28i xDrive
Unlock the sound and response your BMW N20 deserves with the Stone Exhaust Cat-Back Valvetronic Exhaust System. Engineered for the BMW F25 X3 28i and F26 X4 28i xDrive models from 2013 onwards, this premium valved cat-back exhaust delivers a deeper, sportier tone, improved throttle response and exceptional build quality with true OEM-level fitment.
Designed using 3D scanning and reverse engineering of the OEM system, then validated on Stone’s in-house dyno, this BMW N20 cat-back exhaust provides a precision fit and performance you can feel. The Valvetronic setup gives you full control of volume and character at the touch of a button, with On, Off and Auto modes via the plug-and-play OBDII controller.
We have fitted and used Stone Exhaust systems extensively. Our customers love the sound quality, the no-drone cruising and the seamless OEM-style fitment. If you are searching for BMW X3 28i exhaust upgrade, BMW X4 28i xDrive valved exhaust, BMW N20 cat-back exhaust or BMW F25 F26 Valvetronic exhaust, this is the solution.
Why choose this BMW N20 F25 F26 cat-back exhaust
- Valvetronic control - quiet when you want, aggressive when you need
- Plug-and-play OBDII controller with remote - On, Off and Auto RPM-based valve operation
- Eliminates drone commonly found on the standard exhaust system
- One-piece design - engineered for durability and consistent flow
- Mechanical welding with precision - robust, reliable construction
- Developed with 3D scanning and reverse engineering for 100 percent OEM fit
- Dyno developed in house - performance-focused exhaust tuning
Engineering that stands out
Stone Exhaust invests in proper R and D so your BMW exhaust upgrade fits right and performs. Using 3D simulation to map gas flow, thermal zones and pressure, their team optimises pipe routing and diameters for the BMW N20 engine found in the F25 X3 28i and F26 X4 28i xDrive.
Manufacturing highlights include a 7 axis CNC bending process for exceptional roundness and precision, crisscross and overlapping welding for strength in high temperature zones and direct spot welding by mechanical arms for consistent, high penetration joints. The result is a cat-back system that looks as good as it sounds.
Valvetronic control - your sound, your way
Choose your drive mode on the fly. With the Stone Valvetronic remote you can select:
- ON - valves open for maximum sound and flow
- OFF - valves closed for neighbour-friendly, refined cruising
- AUTO - set your preferred RPM for automatic valve operation
The system connects to your OBDII port and is designed for quick, straightforward installation.
Hear it
Stone Valvetronic System Installation
BMW N20 F26 X4 28i xDrive with Stone Exhaust Valvetronic Cat-Back - sound example
Compatibility - BMW N20 engine
- BMW F25 X3 28i - including xDrive variants
- BMW F26 X4 28i xDrive
- Model years 2013 onwards as applicable
Part numbers and tailpipe configurations
- AP541BS - Single exit left with twin tailpipes - requires original bumper
- AP536BS - Dual exit with twin tailpipes - requires M40i bumper
- AP536BSQ - Dual exit with quad tailpipes - requires M Sport bumper
Please select the correct configuration for your bumper style.
Images
R and D - 3D scanning and simulation
Stone Exhaust engineers 3D scan OEM BMW N20 exhaust parts to analyse pipe diameter, route and bend angles, then iterate with simulation to optimise flow and heat management. Progressive improvements lead to an OEM-fit, performance cat-back exhaust that enhances your BMW X3 28i or X4 28i xDrive.
Manufacturing - precision first
With a 7 axis CNC bending machine, Stone achieves outstanding roundness and accuracy, helping maintain smooth airflow and structural integrity. Crisscross and overlapping welding techniques increase tolerance in high temperature zones between components. Direct spot welding by mechanical arms improves precision and penetration for a stronger, longer lasting exhaust.
Warranty
Stone Exhaust 2 year warranty.
Professional fitting - Nforcd Warwickshire
For expert installation of your BMW X3 28i or X4 28i xDrive cat-back Valvetronic exhaust, we recommend our in-house fitting service in Warwickshire. Request a quote at Sales@nforcd.com.
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