Switchable Valve Cat Back System for BMW 1 Series N13 F20 F21
Transform the character of your N13-powered 1 Series with Stone’s valve-controlled cat back. This premium system delivers a calm, refined tone for everyday driving and a sharper, motorsport-inspired soundtrack at the press of a button. Developed with precision, flow optimised and designed to fit like factory, it is the go-to upgrade for 116i, 118i and 120i drivers who want sound, response and quality without compromise.
We have fitted this system for customers and on our own cars. Feedback has been consistently excellent on sound quality, build accuracy and the noticeable improvement in throttle response. If you want your F20 or F21 to feel livelier without cabin drone, this is the one.
Highlights
- Valve-controlled sports exhaust with quiet and sport sound modes
- OBD2 plug-in remote controller with ON, OFF and AUTO functions
- AUTO mode can open the valve by engine speed for intelligent operation
- One-piece run for smooth gas flow and a precise, bolt-on fit
- Engineered via 3D scanning and reverse engineering of the OE system
- Dyno developed to sharpen response and enhance performance feel
- No unwanted resonance for relaxed motorway cruising
- 7-axis CNC bending and high-precision welding for strength and consistency
Sound and driveability
With the valve closed you get a subtle, clean tone that keeps long journeys effortless. Open the valve and the car wakes up with a deeper, crisper note that suits spirited driving and track days. The switchable setup means you control the character, not the other way round.
Smart valve control
- Remote handset included with simple ON, OFF and AUTO options
- OBD-II plug and play installation with no complicated wiring
- RPM-based logic in AUTO for hands-off valve management
Engineered to fit and last
Stone Exhaust has been developing performance systems since 1998. This N13 cat back is designed using advanced simulation to optimise flow, temperature and pressure. 7-axis CNC bending maintains tube roundness, while crisscross and overlapping welds plus direct spot welding reinforce high-stress areas for long-term durability.
Vehicle compatibility
BMW 1 Series with the N13 petrol engine:
- F20 116i, 118i, 120i from 2010+
- F21 116i from 2011+, 118i and 120i from 2012+
Note: requires M135i rear bumper.
Part number
AP515NS
Warranty
Backed by a 2-year Stone Exhaust warranty.
Professional installation
For fitting and setup, book with MJ Modifications in Warwickshire. Email info@mjmodifications.co.uk for a quote.
Search terms customers use
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