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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 10 (of 10 products)
HEATKIT986
Product Information
Product Information
Exhaust Cat Heat protection plate kit.

porsche

Fits:
Porsche Boxster 986 cat.

Click 'Zoom in' for large parts diagram.
Diagram Ref No 17,18, 25, 26 and 27.

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Related, superseded, cross reference or alternative numbers for comparison.

HEATKIT986
99611342200
99611342100
99611342100
99611342200
99950743009
90015100703
99950741308

The product you are viewing cross references to these numbers
Special Order item
99611342
Product Information
Product Information
Exhaust cat heat shield. 

porsche

Another popular item which normally rusts and starts to rattle. Heat protection plate for Porsche Boxster 986 cat.

Price is for each heat shield

Click 'Zoom in' for large parts diagram.
Diagram Ref No 19 and 20


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Related, superseded, cross reference or alternative numbers for comparison.

99611342
99611342200
99611342100

The product you are viewing cross references to these numbers
3606109862
Product Information
Product Information
Exhaust catalytic converter bypass pipe for Porsche Boxster 986

designtek

Manufactured from highest quality T304 grade stainless steel
Mandrel bent and fully TIG welded for strength and durability
CNC machined flanges for strong, solid support and an accurate fit
Designed to improve power and torque across the entire RPM range
Noticeably improves throttle response
Please note fitting instructions are NOT included
Sold for off-road / track use only
We recommend all exhaust components are fitted by a qualified mechanic to ensure the correct fitment

Fits:
Porsche Boxster 986 2.5L / 2.7L / 3.2L

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:
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.

3606109862
996113921AX
996113922AX
99611392101
99611392201
99611302111
99611302112

The product you are viewing cross references to these numbers
FSPOR9861PCB
Product Information
Product Information
Fabspeed Secondary Cat Bypass Pipes.

fabspeed

Replaces the heavy, restrictive, and redundant factory secondary catalytic converters with a straight-through tubing section for increased power, sound, and weight savings.

FEATURES:
Fits: all 986 Boxster / S vehicles (2000-2004)
• Increases horsepower by 8 whp improving throttle response
• Saves 25 lbs from the vehicle versus factory OEM restrictive catalytic converters
• Constructed from high quality T304L stainless steel with CNC mandrel-bent tubing
• Improves horsepower, torque, throttle response and exhaust note
• Easy bolt-on installation; no cutting or welding required
• All Fabspeed performance products are backed by the Fabspeed Lifetime Limited Warranty
• Not UK MOT appoved.

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.

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: 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.

FSPOR9861PCB
98611112109
99611302111
99611302112
996113021AX
99611302502
99611302503
996113025AX
99611302504
996113025BX
99611302211
99611302212
996113022AX
99611302602
99611302603
996113026AX
99611302604
996113026BX

The product you are viewing cross references to these numbers
3606109861
Product Information
Product Information
Exhaust Catalytic Converter Pipes Sports 200 CELL

designtek

DesignTek emissions legal horsepower - throaty sports car sound, but not too loud for every day driving, manufactured from extra heavy duty stainless steel, which eliminates the splitting, cracking and annoying resonance.

Made by DESIGNTEK

Fits:
Porsche Boxster 986 2.7L / 3.2L

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: 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.

3606109861
99611302111
99611302112
996113021AX
99611302502
99611302503
996113025AX
99611302504
996113025BX
99611302211
99611302212
996113022AX
99611302602
99611302603
996113026AX
99611302604
996113026BX

The product you are viewing cross references to these numbers
986PO94360S
Product Information
Product Information
Exhaust Catalytic Converter Pipes Sports 100 CELL

danskmotorsport

Fits:
Porsche 986 Boxster 2.7L / 3.2L 1994-04

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.

Emissions legal horsepower - throaty sports car sound, but not too loud for every day driving, manufactured from extra heavy duty stainless steel, which eliminates the splitting, cracking and annoying resonance.

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.

986PO94360S
99611302111
996113021AX
99611302112
99611302502
996113025AX
99611302504
996113025BX
99611302211
99611302212
996113022AX
99611302602
996113026AX
99611302603
99611302604
996113026BX
99611392101
996113921AX
99611392201
996113922AX

The product you are viewing cross references to these numbers
Special Order item
99950800401
Product Information
Product Information
Heatshield Locking Bolt 6x12. EACH.

porsche

Fits:
Porsche Boxster 986


Click 'Zoom in' for large parts diagram.
Diagram ref no 27

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

99950800401
99950743009
99950800401

The product you are viewing cross references to these numbers
Special Order item
90015100703
Product Information
Product Information
Heatshield Locking Bolt washer 7,4mm . EACH.

porsche

Fits:
Porsche Boxster 986

Click 'Zoom in' for large parts diagram.
Diagram ref no 26

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

90015100703
90015100703
90015100702

The product you are viewing cross references to these numbers
99611302
Product Information
Product Information
Standard Replacement Exhaust Catalytic Converter for Porsche Boxster 986 2.7L / 3.2L 400 Cell

PORSCHE BOXSTER 2.7L & 3.2L S Replacement Type Approved Petrol Cats made in grade 409 stainless steel. Recommend to change in a pair

Fits:
Porsche Boxster 986 2.7L / 3.2L
Note: You will need M8x1x10 Plug (9000838000) & M8x11.5 Seal ring (90012305020) from each original Cat or suitable replacement


A catalytic converter is an emissions control device to stop harmful exhaust gasses from entering the atmosphere. In 1993, they became legality in the UK as part of the Euro Emissions standards. The aim of them is to improve air quality. As emissions standards have become more stringent the number of cats on a vehicle has increased. Many vehicles now have two or more to enable them to meet the Euro Emissions standards.

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
99611302111
996113021AX
99611302112
99611302502
996113025AX
99611302503
99611302504
996113025BX
99611302211
99611302212
996113022AX
99611302602
99611302603
996113026AX
99611302604
996113026BX

The product you are viewing cross references to these numbers
Special Order item
99950741308
Product Information
Product Information
Retaining clip Speed nut. EACH.

porsche

Fits:
Porsche Boxster 986

Diagram ref no 25

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

99950741308
99611342200
99611342100
99950741308
99950741309

The product you are viewing cross references to these numbers
DISPLAYING 1 to 10 (of 10 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.

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