Catalyst / Bypass

The ultimate lightweight cat-back exhaust system for the 991.2 GT3 / GT3 RS saves 54lbs (24kg) off the rear of the vehicle and is perfect for competitive track use, high performance drivers education events, or aggressive street sound.
FEATURES:
• Fits all Porsche 991.2 GT3 / GT3 RS models (2017+)
• Perfect exhaust solution for maximum performance and sound during competitive track use, high performance drivers education events, or simply achieving an aggressive and exciting street sound.
• Saves over 54lbs (24kg) from the rear of the 991.2 GT3 which improves handling and acceleration by replacing the bulky factory center muffler and side mufflers
• Engineered and manufactured with 3" (76mm) T304L stainless steel tubing with integral tuned center X-Pipe to 70mm outlets.
• Bolt-on installation' no cutting or welding required
• Options of 4" Carbon Fiber Tips or 4" Stainless Steel Brushed Tips
• Includes two (2) 90 degree Turndown Tips for track use.
• All Fabspeed performance products are backed by Fabspeed's Limited Lifetime Warranty
NOTE: This is a straight pipe, racing oriented exhaust system built to be light and make power. As a result, the volume level will be very high inside the vehicle.
Please note: These sport cats will make your car sound louder than with stock cats. If you have ,or intend to install sport silencers, you may find the car is a bit loo loud. We recommend to use one sport exhaust component if you are concerned about decibel levels.
NOTE: Sports catalytic converters and bypass pipes do not have type approval and are not legally permitted for use on vehicles manufactured after 1st March 2001 in the United Kingdom. They are not MOT compliant and must not be used on public roads. These components are intended for race and track use only. If you are located outside the UK, please consult your local laws and regulations to ensure compliance.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
FSPOR9912GT3CRX
The product you are viewing cross references to these numbers
- Porsche 991.2 GT3 4.0L (500 Bhp) / GT3 RS 4.0L (520 Bhp) 2017-19
Description Shipping & Returns Direct replacement for the failure-prone OEM GT3 center muffler providing improved flow, weight savings, and more aggressive sports car sound. Our new "Cross Over /talk-pipe" design blends the exhaust from the right and left cylinders creating an incredible smooth blended sound, and our simplified two-bolt mounting system makes installing easier than ever. This is the World's Absolute Best GT3 center muffler replacement bypass system.
FEATURES:
• Fits all Porsche 991.2 GT3 / GT3 RS vehicles 2017- 2019 worldwide
• Saves 10 lbs, 4.6KG from the rear of the vehicle
• CAT-BACK emissions legal. Bolts onto OEM Porsche catalytic converters.
• Retains Sport Mode control button when used with factory GT3 side mufflers. PSE works great.
• 14-16ga T304 Stainless Steel construction- back purged hand TIG welded perfection by craftsmen.
• Works great with Fabspeed GT3 side muffler bypass pipes with or with out Helical OEM GT3 exhaust valves.
• Includes 4" 102mm Deluxe Style Tips in your choice of finish or Re-install factory OEM Porsche GT3 tips and or Fabspeed 90 degree turndowns.
• Fabspeed has carbon fiber tips, polished stainless steel tips, and brushed stainless tips too.
• All Fabspeed performance products are backed by the Fabspeed Lifetime Warranty
Please note: This is a special-order item manufactured to order. In some cases, please allow 4 – 5 weeks for the delivery. Special order items cannot be cancelled from this supplier once your order has been placed.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
FSPOR9912GT3CMB
The product you are viewing cross references to these numbers
- Porsche 991.2 GT3 4.0L (500 Bhp) / GT3 RS 4.0L (520 Bhp) 2017-19

High quality T304 Stainless steel equal length primary tubes. C.N.C. mandrel bent.
Designed for maximum flow and no restriction.
Reduced back pressure and better scavenging. More torque and horsepower across the RPM band.
Fits:
Porsche 991 GT3 3.8L 476 Bhp 2013 - 2017 (A175 engine)
Porsche 991 GT3 RS 4.0L 507 Bhp 2013 - 2017 (A175 engine)
Porsche 911 R 4.0L 507Bhp 2014-2017 (A176 engine)
Please note: This will not fit cars:
- with engine codes DNSA / DNSB - 4.0L with 520 Bhp
- released after 06/2017 with engine codes DGG / DGGA / DGGB
Please note: These sport cats will make your car sound louder than with stock cats. If you have ,or intend to install sport silencers, you may find the car is a bit loo loud. We recommend to use one sport exhaust component if you are concerned about decibel levels.
NOTE: Sports catalytic converters and bypass pipes do not have type approval and are not legally permitted for use on vehicles manufactured after 1st March 2001 in the United Kingdom. They are not MOT compliant and must not be used on public roads. These components are intended for race and track use only. If you are located outside the UK, please consult your local laws and regulations to ensure compliance.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
3606309105
The product you are viewing cross references to these numbers
- Porsche 991.1 R 4.0L (500 Bhp) 2016
- Porsche 991.1 GT3 3.8L (475Bhp) 2014-16
- Porsche 991.1 GT3 RS 4.0L (500Bhp) 2015-16
- Porsche 991.2 GT3 4.0L (500 Bhp) / GT3 RS 4.0L (520 Bhp) 2017-19

High quality T304 Stainless steel equal length primary tubes. C.N.C. mandrel bent.
Designed for maximum flow and no restriction.
Reduced back pressure and better scavenging. More torque and horsepower across the RPM band.
Fits:
Porsche 991.2 GT3 4.0L 500 Bhp 2017-2020 (DGG / DGGA engine)
Porsche 991.2 GT3 RS 4.0L 520 Bhp 2017 - 2020 (DGGB engine)
Please note: This will not fit cars:
- with engine codes DNSA / DNSB - 4.0L with 520 Bhp
Please note: These race cats will make your car sound significantly louder than with stock cats. Race track and off road use only.
We recommend to use one sport exhaust component if you are concerned about decibel levels.
NOTE: Sports catalytic converters and bypass pipes do not have type approval and are not legally permitted for use on vehicles manufactured after 1st March 2001 in the United Kingdom. They are not MOT compliant and must not be used on public roads. These components are intended for race and track use only. If you are located outside the UK, please consult your local laws and regulations to ensure compliance.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
3606309106
The product you are viewing cross references to these numbers
- Porsche 991.1 R 4.0L (500 Bhp) 2016
- Porsche 991.2 GT3 4.0L (500 Bhp) / GT3 RS 4.0L (520 Bhp) 2017-19
In case you need to relocate your existing lambda probe because it's not in the right location. Welding and cutting specialist required.
Fits:
Many Porsche vehicles. Universal kit.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
100390100392
The product you are viewing cross references to these numbers
- Porsche 964 (911) C2 1989-93
- Porsche 964 (911) C4 1989-93
- Porsche 964 (911) RS 3.6L 1991-93
- Porsche 964 (911) RS 3.8L 1991-93
- Porsche 964 (911) TURBO 3.3L 1991-93
- Porsche 964 (911) TURBO 3.6L 1991-93
- Porsche 993 (911) C2 1994-97
- Porsche 993 (911) C4 1994-97
- Porsche 993 (911) RS 1994-97
- Porsche 993 (911) C2S 1994-97
- Porsche 993 (911) C4S 1994-97
- Porsche 993 (911) TURBO 1994-96
- Porsche 993 (911) GT2 1994-97
- Porsche 993 (911) TURBO S 1994-97
- Porsche 996 C2 3.4L 1997-08/01
- Porsche 996 C4 3.4L 1997-08/01
- Porsche 996 C2 3.6L 09/01-2005
- Porsche 996 C4 3.6L 09/01-2005
- Porsche 996 C4S 3.6L 09/01-2005
- Porsche 996 TURBO 2000-05
- Porsche 996 GT2 2001-05
- Porsche 996 GT3 MKI 1999-02
- Porsche 996 GT3 MKII 2003>>
- Porsche 996 GT3 RS 2003-04
- Porsche 997 MK1 Carrera 2 3.6L 2005-08
- Porsche 997 MK1 Carrera 2S 3.8L 2005-08
- Porsche 997 MK1 Carrera 4 3.6L 2005-08
- Porsche 997 MK1 Carrera 4S 3.8L 2005-08
- Porsche 997 MK1 TURBO 2007-09
- Porsche 997 MK1 GT3 2007-09
- Porsche 997 MK1 GT2 2007-09
- Porsche 997 MKII Carrera C2 3.6L 2009-12
- Porsche 997 MKII Carrera C4 3.6L 2009-12
- Porsche 997 MKII Carrera C2S 3.8L 2009-12
- Porsche 997 MKII Carrera C4S 3.8L 2009-12
- Porsche 997 MKII GT3 2010-11
- Porsche 997 MKII Turbo 2010-13
- Porsche 997 MKII GT2 RS 2011-13
- Porsche 991.1 Carrera C2 3.4L (350Bhp) 2012-16
- Porsche 991.1 Carrera C2S 3.8L (400Bhp) 2012-16
- Porsche 991.1 Carrera C4 3.4L (350Bhp) 2012-16
- Porsche 991.1 Carrera C4S 3.8L (400Bhp) 2012-16
- Porsche 991.1 Turbo 3.8L (520bhp) 2014-16
- Porsche 991.1 Turbo S 3.8L (560Bhp) 2014-16
- Porsche 991.1 R 4.0L (500 Bhp) 2016
- Porsche 991.1 GT3 3.8L (475Bhp) 2014-16
- Porsche 991.1 GT3 RS 4.0L (500Bhp) 2015-16
- Porsche 991.2 Carrera 2 3.0L (370 Bhp) 2016-19
- Porsche 991.2 Carrera 2S 3.0L (420 Bhp) 2016-19
- Porsche 991.2 Carrera 4 3.0L (370 Bhp) 2016-19
- Porsche 991.2 Carrera 4S 3.0L (420 Bhp) 2016-19
- Porsche 991.2 Cabriolet 2 3.0L (370 Bhp) 2016-19
- Porsche 991.2 Cabriolet 2S 3.0L (420 Bhp) 2016-19
- Porsche 991.2 Cabriolet 4 3.0L (370 Bhp) 2016-19
- Porsche 991.2 Cabriolet 4S 3.0L (420 Bhp) 2016-19
- Porsche 991.2 Targa 4 3.0L (370 Bhp) 2016-19
- Porsche 991.2 Targa 4S 3.0L (420 Bhp) 2016-19
- Porsche 991.2 Turbo Coupe 3.8L (540 Bhp) 2016-19
- Porsche 991.2 Turbo S Coupe 3.8L (580 Bhp) 2016-19
- Porsche 991.2 Turbo Cabriolet 3.8L (540 Bhp) 2016-19
- Porsche 991.2 Turbo S Cabriolet 3.8L (580 Bhp) 2016-19
- Porsche 991.2 Speedster 4.0L (510Bhp) 2019
- Porsche 991.2 GT3 4.0L (500 Bhp) / GT3 RS 4.0L (520 Bhp) 2017-19
- Porsche 991.2 GT2 RS 3.8L PDK (700 bhp) 2018-19
- Porsche 992.1 Carrera 2 3.0L 2019-24
- Porsche 992.1 Carrera 4 3.0L 2019-24
- Porsche 992.1 Carrera 2 Cabriolet 3.0L 2019-24
- Porsche 992.1 Carrera 4 Cabriolet 3.0L 2019-24
- Porsche 992.1 Carrera 2S 3.0L 2019-24
- Porsche 992.1 Carrera 4S 3.0L 2019-24
- Porsche 992.1 Carrera 2S Cabriolet 3.0L 2019-24
- Porsche 992.1 Carrera 4S Cabriolet 3.0L 2019-24
- Porsche 992.1 Targa 4 3.0L 2020-24
- Porsche 992.1 Targa 4S 3.0L 2020-24
- Porsche 992.1 Speedster 4.0L 2019-24
- Porsche 992.1 Turbo 3.8L 2020-24
- Porsche 992.1 Turbo S 3.8L 2020-24
- Porsche 992.1 Turbo Cabriolet 3.8L 2020-24
- Porsche 992.1 Turbo S Cabriolet 3.8L 2020-24
- Porsche 992.1 GT3 4.0L / 992 S/T 4.0L 2021-24
- Porsche Cayman 2.7L 987C 2006-08
- Porsche Cayman S 3.4L 987C 2005-08
- Porsche Cayman 2.9L 987C MKII 2009-12
- Porsche Cayman S / R 3.4L 987C MKII 2009-12
- Porsche Cayman 2.7L 981 2013-16
- Porsche Cayman S / GTS 3.4L 981 2013-16
- Porsche Cayman GT4 3.8L 2015-16
- Porsche Cayman 718 2.0L Manual (300Bhp)
- Porsche Cayman 718 2.0L PDK (300Bhp)
- Porsche Cayman S 718 2.5L Manual (350Bhp)
- Porsche Cayman S 718 2.5L PDK (350Bhp)
- Porsche Cayman T 718 2.0L Manual (300Bhp)
- Porsche Cayman T 718 2.0L PDK (300 Bhp)
- Porsche Cayman GTS 718 2.5L Manual (365 Bhp)
- Porsche Cayman GTS 718 2.5L PDK (365 Bhp)
- Porsche Cayman GTS 718 4.0L Manual (400 Bhp)
- Porsche Cayman GTS 718 4.0L PDK (400 Bhp)
- Porsche Cayman GT4 718 4.0L / GT4 RS 718 4.0L

Optimized design that replaces the heavy and restrictive factory side mufflers for improved exhaust flow, increased sound and weight savings.
Utilizing premium Helical valves along with the addition of O2 bungs, Fabspeed's Side Muffler Bypass Pipes provide the ultimate track solution for the 991.2 GT3 / GT3 RS. When accompanied with our new Long Tube Competition Headers, our Side Muffler Bypass Pipes allow the maximum amount of exhaust flow possible from the 991.2 GT3 / GT3 RS engine.
HELICAL VALVES
We chose to use Helical Valves on our 991.2 GT3 / GT3 RS track exhaust systems for their unprecedented quality - which have been proven by many OEM manufacturers such as McLaren, Ferrari, Lamborghini, and many more. Helical valves are an integral part of our Side Muffler Bypass pipes, opening and closing with precision to control the gas flow and optimizing engine back-pressure for improved performance. Helical's extensive experience in high-volume OEM automotive applications has led to standard features such as an extremely durable pneumatic actuator, precision flat sealing faces inside the valve, stiffening ribs and high-temperature bearings at both ends of the butterfly spindle.
O2 BUNGS
We relocated the O2 bungs from the collector of the headers to the Side Muffler Bypass Pipes in order to maintain factory-like functionality with our Long Tube Competition Headers - allowing them to read all cylinders while maximizing the performance of the collector. This design will replace our existing SMBP's allowing you to upgrade to our Long Tube Race Header design at any time in the future.
FEATURES:
• Fits all Porsche 991.2 GT3 / GT3 RS vehicles (2017+)
• Highest quality Helical valves
• Includes O2 bungs for factory like functionality when paired with Fabspeed Long Tube Competition Race Headers
• Saves 34 lbs from the rear of the vehicle
• Replicates aggressive CUP car sound for the street
14-16ga T304 Stainless Steel construction
• Simple bolt-on installation
• All Fabspeed performance products are backed by the Fabspeed Lifetime Limited Warranty.
Please note: This is a special-order item manufactured to order. In some cases, please allow 4 – 5 weeks for the delivery. Special order items cannot be cancelled from this supplier once your order has been placed.
NOTE: Sports catalytic converters and bypass pipes do not have type approval and are not legally permitted for use on vehicles manufactured after 1st March 2001 in the United Kingdom. They are not MOT compliant and must not be used on public roads. These components are intended for race and track use only. If you are located outside the UK, please consult your local laws and regulations to ensure compliance.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
FSPOR9912GT3SMB
The product you are viewing cross references to these numbers
- Porsche 991.2 GT3 4.0L (500 Bhp) / GT3 RS 4.0L (520 Bhp) 2017-19

Fits
991.1 and 991.2
Porsche 911 GT3
Porsche 911 GT3 RS
Porsche 911 R
The product can be fitted on 991 R, GT3, GT3 RS models, both 991.1 and 992.2 Not for 997
The component is perfectly interchangeable with the original components, following the instructions in the constructor's workshop manual
RACETRACK USE ONLY
These components are designed and developed for racetrack use and to maximise the car's performance. They are not street legal and must be installed by professionals in the sector
REDUCED CELL CATALYTIC CONVERTER - 300 CELLS
Race catalytic converters have fewer cells than standard factory systems. This reduces exhaust back pressure while still cutting pollutant emissions and boosts power and sound
ECU REMAPPING - ENGINE LIGHT
Replacement or removal of components such as catalytic converters, GPFs and electric actuators may cause the engine warning light to come on. In this case, the installer must reprogram the software to eliminate the light
END TIPS DESIGN - OE
The muffler must be used in conjunction with the original exhaust end tips
MATERIAL - AISI 304 STAINLESS STEEL
A choice stainless steel ideal for aggressive environments where combustion emissions can cause serious chemical corrosion on other types of metal
MAIN PIPE DIMENSION - 80mm
This is the diameter of the main pipe of the exhaust system
NOTE: Sports catalytic converters and bypass pipes do not have type approval and are not legally permitted for use on vehicles manufactured after 1st March 2001 in the United Kingdom. They are not MOT compliant and must not be used on public roads. These components are intended for race and track use only. If you are located outside the UK, please consult your local laws and regulations to ensure compliance.
- Porsche 991.1 R 4.0L (500 Bhp) 2016
- Porsche 991.1 GT3 3.8L (475Bhp) 2014-16
- Porsche 991.1 GT3 RS 4.0L (500Bhp) 2015-16
- Porsche 991.2 GT3 4.0L (500 Bhp) / GT3 RS 4.0L (520 Bhp) 2017-19
Exhaust Catalytic Converters & Bypass Pipes – Performance, Efficiency & Flow Control
The catalytic converter plays a crucial role in your Porsche’s exhaust system, reducing harmful emissions while maintaining optimal exhaust flow. Positioned between the exhaust manifold and silencer, it converts toxic gases such as carbon monoxide, hydrocarbons, and nitrogen oxides into less harmful emissions before they exit the tailpipe.
At Design911, we offer a complete range of catalytic converters and bypass pipes for Porsche vehicles. Our manufacturer-quality converters ensure reliable emission control and long-term performance, while our bypass options are designed for track or performance use, optimising exhaust flow for maximum power and throttle response.
Whether you’re maintaining your Porsche to meet emissions standards or upgrading for improved exhaust performance, our selection includes both direct-fit converters and performance bypass kits built from high-grade stainless steel for strength, corrosion resistance, and durability.
What Do Catalytic Converters & Bypass Pipes Do?
A catalytic converter uses a fine mesh of precious metals to trigger chemical reactions that break down pollutants. The bypass alternative eliminates restriction in the exhaust flow, improving performance in non-emissions-controlled environments such as track driving.
Core Functions:
- Converts
toxic exhaust gases into environmentally friendly emissions.
- Maintains
exhaust back pressure for engine efficiency.
- Reduces harmful NOx, CO, and HC emissions.
- Supports smoother engine performance and throttle control.
- Bypass versions enhance exhaust flow and improve power output for track cars.
Upgrading to a performance-grade system ensures your Porsche continues to meet emission requirements — or achieves greater flow and responsiveness for motorsport applications.
Why Do Catalytic Converters Fail?
Catalytic converters are exposed to extreme heat, unburnt fuel, and contaminants — all of which can degrade their performance over time.
Common Causes of Failure Include:
- Carbon
or oil buildup blocking the internal honeycomb.
- Thermal
damage from overheating or rich fuel mixtures.
- Physical
damage from road debris or misfiring engines.
- Corrosion
due to moisture and exhaust condensation.
- Age-related wear reducing catalytic efficiency.
A failing converter can cause reduced engine power, poor
fuel economy, rattling sounds, or a check-engine light. Replacing it
restores emissions compliance, performance, and exhaust efficiency.
Why Replace or Upgrade
with Precision-Engineered Components?
Replacing a failing converter or upgrading to a bypass pipe ensures your Porsche maintains peak performance and reliability.
Key Benefits:
- Restores optimal emissions performance and efficiency.
- Improves exhaust flow and throttle response.
- Reduces engine stress and fuel consumption.
- Durable stainless-steel construction for longevity.
- Direct-fit
compatibility for Porsche 911, Cayman, Boxster, Panamera, Macan
and more.
- Performance bypass options available for track and tuning applications.
Whether you want emissions compliance or maximum flow for competition use, our parts deliver reliability, precision, and performance.
Highlights:
- Direct-fit catalytic converters and bypass pipes for Porsche models.
- Precision-engineered for optimal flow and reduced emissions.
- Built from heat-resistant stainless steel for durability.
- Bypass pipes for performance tuning and track applications.
- Restores power, efficiency, and exhaust sound balance.
- Available for classic and modern Porsche vehicles.