Fabspeed Side Muffler Bypass Pipes for Porsche 991 GT3 and GT3 RS (2014–2016)

Description

The FABSPEED Side Muffler Bypass Pipes for the 991 GT3 / GT3 RS (2014–2016) ditch the heavy, restrictive factory side mufflers to unlock freer exhaust flow, sharper throttle response, and a raw, aggressive “track-ready” exhaust tone. Engineered for maximum flow, they drop substantial weight from the rear end and transform the exhaust note into an exotic CUP-car-like wail — ideal for track days, spirited drives, or a full performance build. Built from mandrel-bent T304 stainless steel with precision-built valved piping, this kit gives your GT3 a more visceral exhaust personality without sacrificing reliability or quality.

Fitment Notes

• Fits Porsche 911 (991) GT3 and GT3 RS for model years 2014–2019. 

• Designed as a direct bolt-on replacement for factory side mufflers — no cutting or welding required. 

• Includes high-quality valves from Helical — retains exhaust-valve control for variable tone depending on driving conditions. 

• Includes relocated O₂ sensor bungs to ensure factory-like sensor readings even if paired with aftermarket headers.

• Best suited for track-oriented builds or aggressive street/spirited driving; when paired with long-tube headers, these bypass pipes maximize exhaust flow.

Included

• Left and right side muffler bypass pipe assemblies (valved or non-valved version) fabricated in T304 stainless steel. 

• O₂ sensor ports (bungs) for compatibility with factory or aftermarket sensor placement. 

• All required mounting hardware and gaskets for a bolt-on installation — utilizes factory mounting points and exhaust hangers.

• Exhaust valves (Helical brand) with pneumatic actuator for controlled opening/closing depending on driving mode.

Product Specs

• Construction: 14-16 gauge T304 stainless steel, mandrel-bent for smooth flow and strength.

• Weight Savings: Approximately –34 lbs compared to the factory side muffler assemblies.

• Flow Configuration: Valved bypass — valves open under performance conditions for unrestricted flow; valves close to tame sound when desired. 

• Sound Character: Aggressive, exotic exhaust note emulating track-cup cars of Porsche’s racing lineage.

• Finish: Brushed stainless steel as standard; able to handle high exhaust temps and resist corrosion under stress.

Product Features

• Significant Weight Reduction — Shedding 34 lbs from the rear end improves overall handling, throttle response, and reduces unsprung/rear mass.

• Aggressive Cup-Car Sound — Without restrictive mufflers, the exhaust delivers an exotic, high-pitched flat-six scream under throttle and revs.

• Valved Flexibility — Helical valves allow you to control exhaust tone dynamically, balancing street usability and track aggression.

• OEM-Compatible Sensor Setup — O₂ bungs keep factory or aftermarket sensors functional, even with modified exhaust flow.

• Full-Flow Exhaust Path — When combined with race headers, this bypass kit enables maximum flow for peak engine performance.

• Bolt-On Installation — Uses factory mounting points and hardware for a clean install, no fabrication required.

• Durable, Track-Ready Construction — T304 stainless steel with mandrel bends and quality valve actuation ensures longevity under heat and load.

Explore more from our collection.