Stone Exhaust switchable valve system for BMW N55 F30 F31 F32 F33 F36 335i and 435i
Give your turbo six the tone and response it deserves. This from‑catalyst rear section by Stone Exhaust brings a refined soundtrack, crisp throttle feel and OEM‑level fit on BMW 3 Series and 4 Series running the N55 engine. Designed using full chassis scanning and built with premium processes, it delivers the aggressive soundtrack you want when you press on and the calm refinement you need for the daily commute.
Highlights that set it apart
- Factory valve integration for seamless ECU‑controlled quiet and sport operation
- Optional Stone Valvetronic kit for manual control via remote and OBD plug‑in
- Precision pipe geometry achieved through 3D data capture and reverse engineering
- 7‑axis CNC mandrel bends for smooth internal flow and minimal deformation
- Mechanised spot welding and overlapping joints for long‑term durability in high heat zones
- Tight build tolerances for true bolt‑on installation with stock mounting points
- Deep, motorsport‑inspired note under load with low cabin resonance in cruise
How the valve control works
Keep it OEM and let the car’s ECU handle the flap automatically for a factory feel, or add the Stone Valvetronic upgrade to choose quiet or loud at the touch of a button. The optional kit includes an OBD controller and remote so you can switch profiles on demand.
Built with serious engineering
- OEM system digitally modelled to replicate routing, diameter and bend radii for perfect alignment
- Up to 98 percent roundness retained on tight bends to reduce turbulence
- Crisscross and overlapping bead techniques increase strength at critical joints
- Consistency from mechanical welding arms for repeatable quality unit after unit
Real‑world sound and drivability
Closed valves give a calm, comfortable cabin on the motorway. Open the valves and your 335i or 435i rewards you with a sharper, richer N55 growl, quick‑rev character and a confident bark on throttle without the boomy drone that ruins long trips. We have installed these systems for customers and feedback has been consistently positive for tone, refinement and daily usability.
Compatibility
For BMW models with the N55 petrol engine:
- F30 and F31 3 Series 335i, including xDrive
- F32, F33 and F36 4 Series 435i, including xDrive
Part numbers and tailpipe styles
- AP514 - Dual exit with single tailpipe. Requires original bumper.
- AP514Q - Dual exit with quad tailpipes. Requires M Sport bumper.
Fitting and installation
Professional installation recommended. MJ Modifications in Warwickshire offers supply and fit with care and precision. Request a quote at info@mjmodifications.co.uk.
Warranty
Stone Exhaust 2 year warranty.
Manufacturer
Stone Exhaust
Search phrases to help you find this system
BMW F30 335i sports exhaust UK, BMW 335i switchable valve exhaust, BMW 435i performance system, F31 touring exhaust upgrade, F32 coupe flap exhaust, F33 convertible exhaust upgrade, F36 Gran Coupe exhaust UK, N55 stainless performance exhaust, N55 switchable flap system, BMW xDrive compatible exhaust, quad tip exhaust for BMW 435i, quiet to loud exhaust for BMW, ECU integrated valve exhaust, remote valve controller exhaust, premium mandrel bent exhaust for BMW N55, UK BMW specialist exhaust upgrade, MJ Modifications BMW exhaust fitting Warwickshire, AP514 exhaust, AP514Q quad tailpipes.
