Stone MP517S Valvetronic Cat-Back Exhaust for Mercedes-Benz AMG GLC 43 GLC43 (M276 X253/C253 Coupe) – Switchable Active Valve, Remote OBD2 Plug & Play, Drone-Free Performance Sports Catback/Back Box Upgrade

Stone MP517S Switchable Sports System for Mercedes GLC 43 AMG M276, X253 and C253

Turn your GLC 43 AMG into the car it always should have been. The Stone MP517S switchable catback brings a richer soundtrack, sharper response and factory-level fit, without the motorway boom you are trying to avoid. Designed around the M276 twin turbo V6 using full 3D data capture and reverse engineering, it slides into place exactly like the original part and delivers a mature, performance-led tone when the valves are open, with refined cruising when they are closed.

We have installed this system on customer cars at MJ Modifications and the feedback has been outstanding. Owners love the deeper note, the instant valve control via the remote fob and the quality of the welds and pipework. If you are searching for a GLC 43 AMG sound upgrade that is easy to live with day to day, this is the one.

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Highlights that make the difference

• Direct-fit catback for GLC 43 AMG SUV and Coupe with the M276 engine, X253 and C253 platforms
• Switchable valves with handheld controller, choose Open, Closed or Auto for the perfect tone at any time
• OBD plug-in control module for quick setup, no permanent wiring needed
• One-piece layout with precision mechanical welding for strength and longevity
• Engineered using 3D scanning for true OE-style alignment and clearances
• Dyno-developed for improved response and a clean, deep sound without unwanted cabin resonance
• Part number: MP517S

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Active valve control, your way

Open it up for a sporty bark or keep it civil with the valves closed. Auto mode lets you choose an rpm where the valves open automatically, so you can enjoy quiet starts and a more aggressive tone under load. The controller connects at the OBD port for a tidy, fast installation.

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OPF and GPF ready

Running a particulate filter. Stone supplies an OPF delete solution at no additional cost, allowing OPF equipped vehicles to use this catback without throwing faults. No ECU coding required to clear OPF errors.

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Built with precision for the M276 platform

• 7 axis CNC bending for repeatable accuracy
• Up to 98 percent tube roundness at tight 180 degree bends
• Integrally formed pipework with less than 0.025 mm variance to keep flow smooth
• Crisscross and overlapping weld technique for deeper penetration at load points
• Robotic spot welding for consistent strength

From virtual flow simulation to real dyno sessions, Stone optimises routing and diameters to suit the Mercedes 43 AMG V6, delivering that signature Stone tone with performance to match.

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Compatibility

For Mercedes-Benz 43 AMG with M276 V6:

• GLC 43 SUV, chassis code X253, 2015 onwards
• GLC 43 Coupe, chassis code C253, 2015 onwards

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What people search for

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Installation

Professional fitting recommended. MJ Modifications in Warwickshire can install this system for you. For a quotation email info@mjmodifications.co.uk.

Stone valve control installation video:

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Warranty

Backed by a 2 year Stone Exhaust warranty.

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Gallery

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Behind the build

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In short

Want a serious sound upgrade for your GLC 43 without compromise. The Stone MP517S gives you a premium switchable valve system, OE quality fitment and a refined, drone free drive on the motorway. It is the bolt-on catback that makes your Mercedes 43 AMG feel special every time you start it.