Stone Exhaust Valvetronic Cat-Back Exhaust System for Mercedes-Benz C-Class AMG M276 3.0 V6 Biturbo (W205/S205/C205) C400 C450 AMG C43 | No-Drone, Plug & Play OBDII, OPF-Ready

Stone Valved Sports Cat Back for Mercedes C-Class W205 S205 C205 C400 C450 AMG C43

Give your twin turbo V6 the voice it deserves. This Stone Valvetronic cat back transforms the soundtrack and character of the M276-powered C-Class, delivering a deep, motorsport-inspired tone when you want it and civilised cruising when you do not. Precision engineered for the W205 platform across saloon, estate and coupe, it fits like factory, sounds like a thoroughbred and enhances flow for sharper response.

We run this system on customer cars and feedback has been outstanding. Owners praise the superb build, neat alignment, zero cabin resonance on the motorway and the instant switch from refined to rowdy at the press of a button.

Highlights that set it apart

• Switchable valves with handheld controller: Loud, Quiet and Auto RPM logic for true daily-driver versatility
• Resonance free cruising for comfortable long-distance driving
• 3D scanned for OEM-level fit on W205 S205 C205 chassis
• Developed and proven on a dyno for optimised gas flow and response
• One piece layout with beautifully executed machine welding for strength and durability
• Simple OBD port control module for fast installation and reliable valve operation
• OPF and GPF compatible solution included for filtered cars without fault lights or coding

How the valve control works

Choose Loud to open the valves and unleash a rich AMG character. Select Quiet for early starts and relaxed town driving. Use Auto to let RPM-based logic manage the valves for you, blending comfort and excitement seamlessly. The controller plugs into the OBD port for a tidy, reversible setup.

Crafted for performance and longevity

Stone engineers start by digitising the factory system to perfect diameter, routing and bend angles. A 7 axis CNC bender maintains roundness through the bends to minimise turbulence. Overlapping and crisscross TIG welding techniques, applied by robotic arms, deliver excellent penetration and a clean finish that lasts.

Compatibility

M276 3.0 V6 biturbo C-Class models:

• W205 C400 2014 onwards
• W205 C450 AMG 2015 onwards
• W205 AMG C43 2016 onwards
• S205 C400 2015 onwards
• S205 C450 AMG 2015 onwards
• C205 C400 2015 onwards
• C205 AMG C43 2016 onwards

What you can expect on the road

• A purposeful, premium tone that complements the twin turbo V6
• Smooth, drone free cabin at motorway speeds
• Quicker rev pickup thanks to improved exhaust scavenging
• Factory-style integration with neat tips and perfect symmetry

Installation and fitting

Professional fitting recommended. MJ Modifications offers expert installation in Warwickshire with careful alignment and valve calibration. Request a quote at info@mjmodifications.co.uk.

Part number and warranty

Part Number MP512S

Brand Stone Exhaust

Warranty 2 year manufacturer warranty

R and D detail

Thermal load, pressure distribution and gas velocity are simulated during development, then validated on the dyno. Tight tolerances ensure consistent fitment across W205 saloon, S205 estate and C205 coupe variants.

Media

Installed gallery

Sound clips and install video

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