Please wait… 
Please wait while we process your order,
do not press the back button… 
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

Filter by brand
DISPLAYING 1 to 8 (of 8 products)
3606109915
Product Information
Product Information
A Voucher for £100 available when you buy this product. For more information CLICK HERE

DesignTek Exhaust manifold / header with 200 Cell Euro 4 coating substrate.
Price is for PAIR.

designtek

Fits:
Porsche 991.1 Carrera / S

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Related, superseded, cross reference or alternative numbers for comparison.

3606109915
3606109875
99111341104
991113411AX
99111341202
99111341204
991113412AX

The product you are viewing cross references to these numbers
3606109918
Product Information
Product Information
A Voucher for £100 available when you buy this product. For more information CLICK HERE

DesignTek Exhaust manifold / header with catalyst bypass.
Price is for PAIR.

designtek

Fits:
Porsche 991.1 Carrera / S

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Related, superseded, cross reference or alternative numbers for comparison.

3606109918
99111341104
991113411AX
99111341202
99111341204
991113412AX

The product you are viewing cross references to these numbers
3606109919
Product Information
Product Information
A Voucher for £100 available when you buy this product. For more information CLICK HERE

DesignTek Exhaust manifold / header with catalyst bypass.
Price is for PAIR.

designtek

Fits:
Porsche 991.1 Carrera 3.4L 2012-2015
Porsche 991.1 Carrera S 3.82012-2015


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.

3606109919
99111341104
991113411AX
99111341202
99111341204
991113412AX

The product you are viewing cross references to these numbers
3606009130
Product Information
Product Information
Exhaust Muffler / Sport Switchable Race Exhaust System in Titanium DesignTek. With Cat bypass pipes.

designtek

Fits:
Porsche 991.1 S 3.8L

High quality titanium exhaust system for the Porsche 991.1. Manifold back exhaust that includes Catalytic converter bypass and tailpipes.

The silencers in this exhaust are linked to one another, creating a greater balance between the two silencers which improves flow, performance and provides a sports sound. It is a performance exhaust with a louder note and boasts significant power gains over OE system. This is race / offroad use only.

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.
99711152000/1
Product Information
Product Information
Exhaust sleeve catalytic converter to silencer.
Connecting sleeve from cat to rear silencer.
Price is for each sleeve.

oematch

Fits:
Porsche 996 1998-05 (not Turbo and GT2)

Porsche 997 2005>> (not Turbo and GT2)

Porsche 991 Carrera C2 3.4L (350Bhp)
Porsche 991 Carrera C2S 3.8L (400Bhp)
Porsche 991 Carrera C4 3.4L (350Bhp)
Porsche 991 Carrera C4S 3.8L (400Bhp)
   Fits cars with and without sport exhaust

Click 'Zoom in' for large parts diagram.
Diagram ref no 13



Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

99711152000
99711152000
99611122002

The product you are viewing cross references to these numbers
Special Order item
99711152000
Product Information
Product Information
Exhaust sleeve catalytic converter to silencer.
Price is for each sleeve.

porsche

Original Porsche connecting sleeve from cat to rear silencer.

Fits:
Porsche 997 2005>> (not Turbo and GT2)
    Fits cars with and without sport exhaust

Porsche 991 Carrera C2 3.4L (350Bhp)
Porsche 991 Carrera C2S 3.8L (400Bhp)
Porsche 991 Carrera C4 3.4L (350Bhp)
Porsche 991 Carrera C4S 3.8L (400Bhp)

Click 'Zoom in' for large parts diagram.
Diagram ref no 13



Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

99711152000
99711152000

The product you are viewing cross references to these numbers
99711152000/2
Product Information
Product Information
Titanium (grade 5) Exhaust sleeve catalytic converter to silencer.
Connecting sleeve from cat to rear silencer. Price is for each sleeve.

rohler

Fits:
Porsche 996 1998-05 (not Turbo and GT2)
Porsche 997 2005>> (not Turbo and GT2)
Porsche 991 Carrera C2 3.4L (350Bhp)
Porsche 991 Carrera C2S 3.8L (400Bhp)
Porsche 991 Carrera C4 3.4L (350Bhp)
Porsche 991 Carrera C4S 3.8L (400Bhp)

Fits cars with and without sport exhaust
Grade 5 titanium is resistant to salt water and variety of corrosive media temperatures below 300°C

Click 'Zoom in' for large parts diagram.
Diagram ref no 13



Related reference numbers
Related, superseded, cross reference or alternative numbers for comparison.

99711152000
99711152000

The product you are viewing cross references to these numbers
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
DISPLAYING 1 to 8 (of 8 products)
Also found on these pages
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.

You may also like
Popular Models