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Catalyst / Bypass

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9M99711303402
Product Information
Product Information

Ninemeister sports catalytic converters for Porsche 997.1. Manufactured from lightweight SS304L stainless steel, these replacement catalysts use Belgium-made TriCore 300-cell cores to increase exhaust flow while retaining catalytic gas treatment.

Fits:

  • 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


What This Product Does

These sports catalysts replace the original catalytic converter sections within the exhaust system. Their higher-flow construction reduces back pressure and allows exhaust gases to pass more freely, while the catalytic cores continue to convert carbon monoxide, hydrocarbons and nitrogen oxides. The resulting installation is designed to provide a more pronounced exhaust note and save 2.5 kg compared with the original arrangement.


Functions

  • Replaces the original Porsche 997.1 catalytic converter sections
  • Uses 300-cell catalyst cores to support increased exhaust flow
  • Reduces exhaust back pressure
  • Treats carbon monoxide, hydrocarbons and nitrogen oxides
  • Produces a more sporting exhaust note
  • Provides a stated weight saving of 2.5 kg


Technical Details

  • Lightweight SS304L stainless-steel construction
  • Belgium-made TriCore 300-cell catalytic converters
  • Two-part catalyst construction within each downpipe
  • Three-spiral metallic carrier structure designed to resist pressure waves and exhaust pulses
  • Effective operating temperature: 480–1470°F; short-term tolerance: 1650–1830°F; long-term tolerance: no more than 1560°F
  • Manufacturer-described as MOT compliant and designed to operate without a catalyst-related check-engine light

The purification coating uses platinum, palladium and rhodium. Platinum supports the oxidation of carbon monoxide and hydrocarbons, palladium assists with unburnt hydrocarbon conversion, and rhodium provides nitrogen-oxide reduction. The manufacturer specifies Euro 6 standard purification coatings with a high density of precious metals.


Symptoms of Fault

  • Catalyst-efficiency warning or check-engine light
  • Rattling caused by a damaged internal substrate
  • Restricted exhaust flow or reduced engine response
  • Unusual exhaust smells or excessive heat
  • Exhaust leakage around the catalyst flanges or joints
  • Failure to meet the required emissions limits during testing


Why Replacement Matters

A deteriorated or obstructed catalyst can restrict exhaust flow, create rattling noises and cause emissions-related faults. These Ninemeister replacements combine higher-flow 300-cell cores with stainless-steel downpipes, making them suitable when renewing worn original units or changing the exhaust for reduced back pressure and a stronger exhaust note. Persistent misfires, oil consumption or over-fuelling should be corrected before installation, as prolonged exposure to excessive exhaust temperatures can shorten catalyst life.

FAQs

  • What cell density do these catalysts use? They contain TriCore 300-cell catalytic converter cores.
  • What are the downpipes made from? The construction uses lightweight SS304L stainless steel.
  • Will they cause a check-engine light? Ninemeister describes the product as producing no catalyst-related CEL, provided the vehicle and its emissions-control components are operating correctly.
  • Are they MOT compliant? The manufacturer lists the catalysts as MOT compliant, although the result of an emissions test also depends on the condition and calibration of the vehicle.


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

9M99711303402
99711303304
99711303305
99711303306
997113033AX
99711303500
99711303501
99711303503
99711303504
99711303505
997113035AX
99711303402
99711303404
99711303405
99711303406
997113034AX
99711303600
99711303601
99711303603
99711303604
99711303605
997113036AX

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DISPLAYING 17 to 17 (of 17 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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