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Catalyst / Bypass
- Porsche 996 C2 3.6L 09/01-2005
- Porsche 996 C4 3.6L 09/01-2005
The Fabspeed Porsche 996 Carrera Competition Link Pipe / Cat Bypass X-Pipe is a performance exhaust component designed for closed-course competition and off-road applications. It replaces the factory catalytic-converter section with a freer-flowing X-pipe, reducing exhaust restriction and allowing the Porsche flat-six engine to breathe more efficiently at higher engine speeds.
Fits:
- Porsche 996 C2 3.6L 1999-2004
- Porsche 996 C4 3.6L 1999-2004
Manufactured from mandrel-bent T304L stainless steel, the system is designed to improve mid- and high-RPM performance, sharpen throttle response, reduce rear-end weight and create a significantly more aggressive exhaust note.
Because this system eliminates the factory catalytic converters, it is intended strictly for closed-track and off-road use where legally permitted and should not be used on public roads where catalytic converters are required.
What This Product Does:
The standard Porsche 996 Carrera exhaust system uses catalytic converters to reduce harmful exhaust emissions.
For dedicated competition applications, the Fabspeed Cat Bypass X-Pipe replaces this catalytic-converter section with unrestricted exhaust tubing and an X-pipe crossover.
Removing the catalyst restriction allows exhaust gases to pass through the system more freely.
The system is designed to:
- Reduce exhaust backpressure
- Improve exhaust-gas flow
- Improve mid- and high-RPM performance
- Increase horsepower potential
- Increase torque
- Improve throttle response
- Reduce exhaust-system weight
- Produce a louder, more aggressive exhaust note
- Improve high-RPM engine breathing
Performance Benefits:
Fabspeed reports dyno-tested improvements of:
Horsepower: +33 WHP
Torque: +41 ft-lb
Weight Reduction: Approx. 25 lb
Fabspeed states that the system was developed to deliver its strongest gains towards the upper part of the rev range, with substantial improvements above approximately 3,500 rpm.
These are manufacturer-reported results from a particular test vehicle and are not guaranteed figures for every Porsche 996 Carrera.
Actual performance can vary according to engine condition, vehicle specification, existing modifications, ECU calibration, fuel, atmospheric conditions and testing method.
Why Upgrading Matters:
This component is primarily a competition performance upgrade, not a routine replacement for a failed factory catalytic converter.
For suitable closed-course vehicles, potential reasons for installation include:
- Reduced exhaust restriction
- Increased high-RPM exhaust flow
- Improved mid- and high-RPM performance
- Reduced rear-end weight
- Sharper throttle response
- More aggressive exhaust sound
- Simplified competition exhaust configuration
It can also form part of a broader competition exhaust package incorporating performance headers, lightweight mufflers and other track-oriented modifications.
- Porsche 996 GT3 MKI 1999-02
- Porsche 996 GT3 MKII 2003>>
The Fabspeed Porsche 996 GT3 Cat Bypass X-Pipe is a high-performance competition exhaust component designed to replace the factory catalytic converters with a freer-flowing X-pipe arrangement.
Fits:
- Porsche 996 GT3 MKI 1999-02
- Porsche 996 GT3 MKII 2003>>
Developed for track and competition-focused Porsche 996 GT3 applications, the system removes the restrictive catalytic-converter section and provides a more direct route for exhaust gases leaving the engine.
By reducing exhaust restriction and allowing gases from both cylinder banks to merge through the X-pipe, the system is designed to improve exhaust flow, sharpen throttle response, reduce weight and produce a considerably more aggressive GT3 exhaust note.
What This Product Does:
The original catalytic converters form part of the vehicle's emissions-control system.
While catalysts treat exhaust gases, their internal substrates also create resistance to exhaust flow.
The Fabspeed Cat Bypass X-Pipe removes this catalytic restriction and replaces it with freer-flowing exhaust pipework.
The system is designed to:
- Remove the restrictive factory catalytic converters
- Increase exhaust-gas flow
- Reduce exhaust backpressure
- Improve engine breathing
- Improve throttle response
- Increase horsepower and torque potential
- Reduce exhaust-system weight
- Increase exhaust volume
- Produce a more aggressive motorsport-inspired sound
Because the catalytic converters are removed, this is fundamentally different from a Sport Cat system.
X-Pipe Design:
An X-pipe connects the exhaust streams from the two cylinder banks.
Rather than keeping both exhaust paths completely separate, the crossover allows pressure pulses from each bank to interact.
A properly designed X-pipe can help:
- Balance exhaust pulses
- Improve gas-flow transitions
- Reduce turbulence
- Improve exhaust scavenging
- Support high-RPM performance
- Create a smoother, more exotic exhaust tone
This is particularly suited to the naturally aspirated, high-revving flat-six engine used in the 996 GT3.
Maximum Exhaust Flow:
Removing the catalytic substrates eliminates one of the major restrictions in the exhaust system.
This creates a substantially more open exhaust route.
Potential benefits include:
- Reduced exhaust backpressure
- Faster exhaust evacuation
- Improved engine breathing
- Sharper throttle response
- Stronger high-RPM performance
- Increased performance potential
Actual performance depends on the complete vehicle configuration.
Why Upgrading Matters:
The factory catalytic converters do not need to have failed for this component to be installed.
The Cat Bypass X-Pipe is primarily a competition performance upgrade.
Reasons for upgrading include:
- Maximum exhaust-gas flow
- Elimination of catalytic-converter restriction
- Reduced exhaust backpressure
- Improved throttle response potential
- Increased horsepower and torque potential
- Reduced exhaust-system weight
- More aggressive GT3 exhaust sound
- Improved high-RPM exhaust character
- X-pipe crossover design
- Track-focused configuration
It is particularly suited to vehicles where performance and exhaust flow take priority over road-use emissions requirements.
NOTE: In the United Kingdom, 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. They are not MOT compliant and cannot be used on public roads. These components are intended solely for race and track use.
For vehicles manufactured before 1st March 2001, a non-type approved sports catalytic converter may be fitted, provided it offers comparable performance to the original and the vehicle continues to meet the applicable emissions standards for its age. The vehicle must still pass an MOT test.
If you are located outside the UK, please check your local laws and regulations to ensure compliance.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
FSPOR996GT3CBX
The product you are viewing cross references to these numbers
- Porsche 996 GT3 MKI 1999-02
- Porsche 996 GT3 MKII 2003>>
The Fabspeed Porsche 996 GT3 Sport Cat X-Pipe is a high-performance catalytic converter and X-pipe upgrade designed to improve exhaust flow, throttle response, power and exhaust sound while retaining catalytic exhaust treatment.
Fits:
- Porsche 996 GT3 MKI 1999-02
- Porsche 996 GT3 MKII 2003>>
Replacing the original catalytic-converter section, the system combines 200-cell HJS high-flow Sport Catalytic Converters with a specially designed stainless-steel cast X-pipe featuring a knife-edged internal design. The result is a less restrictive exhaust path that allows gases from the naturally aspirated GT3 flat-six to flow more efficiently through the exhaust system.
Manufactured using mandrel-bent T304L stainless steel, the system is designed as a direct bolt-on performance upgrade requiring no cutting or welding.
Fabspeed reports gains of up to 15 wheel horsepower, together with approximately 14 lb-ft of torque and a 12 lb weight reduction compared with the factory components. Actual results depend on the individual vehicle and testing conditions.
What This Product Does:
The catalytic converters sit within the exhaust system and process exhaust gases before they leave the vehicle.
At the same time, their internal construction creates some resistance to exhaust flow.
A performance Sport Cat system aims to maintain catalytic treatment while reducing unnecessary restriction compared with the original catalytic-converter arrangement.
The Fabspeed Sport Cat X-Pipe is designed to:
- Improve exhaust-gas flow
- Reduce exhaust restriction
- Improve throttle response
- Increase horsepower and torque potential
- Reduce exhaust-system weight
- Produce a more defined GT3 exhaust note
- Provide a mild increase in exhaust volume
- Retain catalytic exhaust treatment
- Improve exhaust flow between the two cylinder banks
Manufacturer Report Performance:
Fabspeed reports curve gains of up to approximately:
Power: +15 WHP
Torque: +14 lb-ft
Weight Reduction: Approx. 12 lb
These are manufacturer-reported figures and should not be interpreted as guaranteed gains for every vehicle.
Actual performance can vary according to:
- Engine condition
- Existing exhaust configuration
- Headers
- Rear muffler system
- Intake modifications
- Engine calibration
- Fuel quality
- Ambient conditions
- Vehicle specification
- Dyno equipment and testing procedure
Why Upgrading Matters:
The factory catalytic converters do not need to have failed for this system to be installed.
The Fabspeed Sport Cat X-Pipe is primarily a performance upgrade designed for drivers seeking improved exhaust flow without moving to a completely catless exhaust section.
Reasons for upgrading include:
- 200-cell HJS Sport Catalytic Converters
- Reduced exhaust restriction
- Cast stainless-steel X-pipe
- Knife-edged X-pipe design
- Improved exhaust-gas flow
- Improved throttle response
- Manufacturer-reported gains up to +15 WHP
- Manufacturer-listed +14 lb-ft torque
- Approx. 12 lb weight reduction
- More defined GT3 exhaust sound
- Mild increase in exhaust volume
- T304L stainless-steel construction
- Mandrel-bent tubing
- Direct bolt-on installation
- No cutting or welding required
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
FSPOR996GT3SCX
The product you are viewing cross references to these numbers
- Porsche 996 C2 3.6L 09/01-2005
- Porsche 996 C4 3.6L 09/01-2005
The Fabspeed Porsche 996 Carrera Sport Catalytic Converter X-Pipe is a high-performance exhaust upgrade designed to replace the restrictive factory catalytic-converter section while retaining catalytic emissions treatment.
Fits:
- Porsche 996 C2 3.6L 1999-2004
- Porsche 996 C4 3.6L 1999-2004
Combining a specially developed X-pipe crossover with integrated 200-cell HJS Sport Catalytic Converters, the system is designed to improve exhaust-gas flow, increase horsepower and torque, reduce rear-end weight and enhance the distinctive Porsche flat-six exhaust note.
Constructed from mandrel-bent T304L stainless-steel tubing, the system provides a performance-focused alternative to the factory catalytic converters without using catalyst-bypass pipes.
What This Product Does:
The catalytic-converter section performs two important functions within the exhaust system.
First, it routes exhaust gases from the engine towards the rear mufflers. Second, the catalytic converters chemically process harmful exhaust pollutants before the gases leave the vehicle.
The Fabspeed Sport Catalytic Converter X-Pipe retains catalytic-converter functionality while providing a higher-flow exhaust path.
Its design is intended to:
- Reduce exhaust restriction
- Improve exhaust-gas flow
- Improve mid-range torque
- Improve high-RPM horsepower
- Enhance throttle response
- Reduce exhaust-system weight
- Produce a more sporting flat-six exhaust note
- Retain catalytic emissions treatment
Performance Benefits:
Fabspeed reports dyno-tested improvements of:
Horsepower: +25 WHP
Torque: +32 ft-lb
Weight Reduction: Approximately 11 lb
These figures are manufacturer-reported results and should not be considered guaranteed output for every vehicle.
Actual performance can vary depending on:
- Engine condition
- Vehicle specification
- Fuel quality
- Existing exhaust modifications
- Intake modifications
- ECU calibration
- Ambient conditions
- Dyno type and testing procedure
Why Upgrading Matters:
The Fabspeed Sport Catalytic Converter X-Pipe is also a performance upgrade, meaning the original catalytic converters do not need to have failed before the system can be installed.
Owners may choose the upgrade for:
- Increased exhaust flow
- Reduced exhaust restriction
- Improved mid-range torque
- Improved high-RPM horsepower
- Enhanced flat-six exhaust sound
- Reduced exhaust-system weight
- High-flow HJS catalytic converters
- Performance-oriented X-pipe design
It can also complement other upgrades such as performance headers, rear mufflers, intake modifications and suitable ECU calibration.
- 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 / GT3 RS 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 / GT3 RS 2010-11
- Porsche 997 MKII Turbo 2010-13
- Porsche 997 MKII GT2 RS 2011-13
- Porsche 991.1 Carrera C2 3.4L (350 Bhp) 2012-16
- Porsche 991.1 Carrera C2S / GTS 3.8L (400/430 Bhp) 2012-16
- Porsche 991.1 Carrera C4 3.4L (350 Bhp) 2012-16
- Porsche 991.1 Carrera C4S / GTS 3.8L (400/430 Bhp) 2012-16
- Porsche 991.1 Turbo 3.8L (520 Bhp) 2014-16
- Porsche 991.1 Turbo S 3.8L (560 Bhp) 2014-16
- Porsche 991.1 R 4.0L (500 Bhp) 2016
- Porsche 991.1 GT3 3.8L (475 Bhp) 2014-16
- Porsche 991.1 GT3 RS 4.0L (500 Bhp) 2015-16
- Porsche 991.2 Carrera 2 3.0L (370 Bhp) 2016-19
- Porsche 991.2 Carrera 2S / GTS 3.0L (420/450 Bhp) 2016-19
- Porsche 991.2 Carrera 4 3.0L (370 Bhp) 2016-19
- Porsche 991.2 Carrera 4S / GTS 3.0L (420/450 Bhp) 2016-19
- Porsche 991.2 Cabriolet 2 3.0L (370 Bhp) 2016-19
- Porsche 991.2 Cabriolet 2S / GTS 3.0L (420/450 Bhp) 2016-19
- Porsche 991.2 Cabriolet 4 3.0L (370 Bhp) 2016-19
- Porsche 991.2 Cabriolet 4S / GTS 3.0L (420/450 Bhp) 2016-19
- Porsche 991.2 Targa 4 3.0L (370 Bhp) 2016-19
- Porsche 991.2 Targa 4S / GTS 3.0L (420/450 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 / GTS 3.0L 2019-24
- Porsche 992.1 Carrera 4S / GTS 3.0L 2019-24
- Porsche 992.1 Carrera 2S / GTS Cabriolet 3.0L 2019-24
- Porsche 992.1 Carrera 4S / GTS Cabriolet 3.0L 2019-24
- Porsche 992.1 Targa 4 3.0L 2020-24
- Porsche 992.1 Targa 4S / GTS 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 (300 Bhp)
- Porsche Cayman 718 2.0L PDK (300 Bhp)
- Porsche Cayman S 718 2.5L Manual (350 Bhp)
- Porsche Cayman S 718 2.5L PDK (350 Bhp)
- Porsche Cayman T 718 2.0L Manual (300 Bhp)
- 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
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 996 C2 3.4L 1997-08/01
- Porsche 996 C4 3.4L 1997-08/01
Not suitable for cars with stricter emissions M661
We recommend you change cats in a pair. For cars with only 2 lambda sensors like the Porsche Carrera 996 3.4L models please also buy Code: EXHFITTING.996.1.1
PORSCHE 996 Carrera 3.4L Replacement Cats made in grade 409 stainless steel.
Fits:
Porsche Carrera 3.4L
Our cat is made up of the following components:
- Ceramic monolith of a honeycomb design to allow free air flow and maximum surface area, coated with precious metals to enable the conversion of gasses that pass through it
- Interam matting to hold the monolith in place. The matting expands when exposed to heat to supply the pressure needed to keep the monolith secure
- A grade 409 stainless steel can (or housing) to provide protection and enable the cat to be built into the exhaust system. 409 grade can contain upto 90% iron and will be prone to rust. It still has higher rust-resistant properties than mild steel.
Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.
99611302
The product you are viewing cross references to these numbers
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.