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Design 911 Design 911 supply Porsche parts, Porsche spares and Porsche accessories, to both retail and to the trade. Our Porsche product and accessory range includes brakes, exhausts, tyres, wheels and Porsche panels and interiors. https://design91.uk/images/schemaLogo.png https://design91.uk/images/schemaLogo.png +443456003478 https://design91.uk Facebook Instagram

Catalyst / Bypass

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DISPLAYING 1 to 4 (of 4 products)
Special Offer
3606309105
Product Information
Product Information
Headers with 300 Cell Race Cats

designtek

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Related, superseded, cross reference or alternative numbers for comparison.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
9A111302190
9A1113021CX
9A111302191
9A1113021AX
9A111302290
9A1113022CX
9A111302291
9A1113022AX

The product you are viewing cross references to these numbers
Special Offer
3606309106
Product Information
Product Information
Headers with Race Cat bypass

designtek

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
9A111302195
9A1113021FX
9A111302295
9A1113022FX

The product you are viewing cross references to these numbers
Special Offer
100390100392
Product Information
Product Information
Lambda Sensor Blanking Plug and Receiver Socket Set.
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
100390
100392

The product you are viewing cross references to these numbers
TSPO991GT306.073.A
Product Information
Product Information
Sports exhaust manifold and catalytic converter kit Porsche 991 GT3 GT3 RS and R

tubi

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.
DISPLAYING 1 to 4 (of 4 products)
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About Catalyst / Bypass

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.

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