Stone Exhaust BMW M3/M4 F80 F82 S55 OPF/GPF/PPF-Back Valved (Valvetronic) Sports Exhaust - OEM Valve Control, Cat-Back/Backbox/Axle-Back Upgrade, Quad Tips, No Drone, Dyno Proven 2014-2018

BMW M3 F80 and M4 F82 S55 GPF Back Valved Cat Back Exhaust by Stone Exhaust

Looking to upgrade the sound and flow on your S55-powered M3 or M4 without compromise. This Stone Exhaust particulate filter back system replaces the factory rear section from the GPF onwards, delivering a deeper motorsport tone, proven power gains and factory-style valve operation using the original actuators. It is a premium upgrade for drivers searching for BMW M3 F80 cat back, BMW M4 F82 sports exhaust, S55 exhaust upgrade with valves, quad exit tailpipes and a drone-free daily driving experience.

Crafted through 3D scanning and reverse engineering of the OE layout, the system slots in perfectly and keeps your drive modes working exactly as they should. With the valves open it offers a crisp, aggressive note, and with the valves closed it is refined for long motorway runs with minimal cabin resonance.

Key reasons enthusiasts choose this upgrade

• Factory valve motors reused for seamless drive mode control and authentic integration
• Back-to-back dyno testing shows real gains and sharper throttle response
• No unwanted interior boom at cruising speeds for comfortable daily use
• Precision pipework and beautifully consistent welds for long-term durability
• 3D scanned for exact fitment on F80 M3 Saloon and F82 M4 Coupe
• Optional dual-valve remote kit available via a plug and play OBDII controller
• Dual exits with four tailpipes for the classic M look

Performance you can feel

Measured gains:

• +12.2 PS at 6800 rpm
• +9.8 Nm at 2500 rpm

This GPF back upgrade improves exhaust gas velocity and unlocks the S55’s characterful soundtrack. Expect crisper response, a richer tone and a more engaging drive, all while retaining day-to-day refinement.

Intelligent engineering and build quality

Stone Exhaust uses comprehensive 3D digitising of the OE system to optimise routing, diameter and bend radii. Computational analysis is employed to study flow and thermal behaviour, then prototypes are iterated until sound and performance targets are met with perfect fit.

Pipework is formed on a state-of-the-art 7-axis CNC bending machine for exceptional roundness, even at tight 180 degree bends, reducing turbulence and stress. Overlapping and crisscross weld techniques maximise penetration and longevity at high-heat joints, while precise spot welding ensures consistent alignment. The result is a robust performance exhaust that looks as good as it sounds.

Compatibility

S55 engine applications:

• BMW F80 M3 Saloon 2012 to 2015
• BMW F80 LCI M3 Saloon 2015 to 2018
• BMW F82 M4 Coupe 2013 to 2017
• BMW F82 LCI M4 Coupe 2016 to 2018

Perfect for drivers searching for

BMW M3 F80 cat back exhaust, BMW M4 F82 exhaust system with valves, S55 performance exhaust, GPF back exhaust for BMW, quad exit M3 M4 exhaust, sports exhaust for BMW M3, M4 back box and mid section upgrade, M3 resonant exhaust, M4 valved cat-back, F80 M3 quad tips, F82 M4 quad tips, flap-controlled exhaust for S55, ECU-controlled valve exhaust, drone-free BMW exhaust.

Our experience

We have installed multiple Stone Exhaust systems at MJ Modifications and customer feedback has been consistently positive. Fitment is spot on thanks to the 3D scanned design, the tone is addictive with valves open and civil with valves closed, and the reduction in cabin resonance compared with stock is impressive. If you want an S55 exhaust that sounds right, performs and integrates with your factory controls, this is the one.

Installation at MJ Modifications

Professional fitting available at MJ Modifications in Warwickshire. For a quotation or to book an appointment, email info@mjmodifications.co.uk.

Part number

AP507-OPFBack

Warranty

Stone Exhaust 2 Year Warranty

Media

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