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- Porsche 964 (911) TURBO 3.3L 1991-93
- Porsche 964 (911) TURBO 3.6L 1991-93
The Fabspeed Porsche 964 Turbo / 965 / C2 Turbo Cat Bypass Pipe is a high-performance stainless steel exhaust component developed for Porsche 911 Turbo models manufactured between 1990 and 1994.
Fits:
- Porsche 964 (911) TURBO 3.3L 1991-93
- Porsche 964 (911) TURBO 3.6L 1991-93
Designed by Fabspeed Motorsport, this competition exhaust pipe replaces the original Porsche catalytic converter with a freer-flowing exhaust connection between the K27 turbocharger and the factory secondary muffler.
Manufactured from premium 14–16 gauge T304L stainless steel, the bypass pipe features CNC mandrel-bent tubing and a 3.0-inch (76 mm) diameter to support efficient exhaust gas flow.
Its design incorporates a four-bolt flange connection and follows the concept of Porsche's original racing exhaust components.
By replacing the restrictive factory catalytic converter, the Fabspeed bypass pipe is designed to reduce exhaust backpressure downstream of the turbocharger, improve exhaust gas flow and enhance the distinctive sound of the turbocharged air-cooled flat-six engine.
The freer-flowing arrangement allows more of the turbocharger's characteristic whistle and spool-up sound to be heard, creating a more pronounced sports car exhaust character.
Fabspeed describes the system as producing an engaging exhaust note without becoming excessively loud when used with the compatible original rear muffler arrangement.
The bypass pipe is designed as a direct bolt-on replacement, allowing the original catalytic converter to be retained separately and refitted when required.
Its stainless steel construction provides resistance to corrosion and thermal deterioration, making it suitable for demanding competition environments.
The product is intended for owners of Porsche 964 Turbo and 965 vehicles seeking a dedicated competition exhaust configuration rather than a standard road-going catalytic converter replacement.
Important: This product removes the factory catalytic converter and is intended exclusively for closed-course motorsport and off-road applications where permitted. It must not be used on public roads.
What This Product Does:
The Fabspeed Cat Bypass Pipe replaces the factory catalytic converter with a straight-through, high-flow exhaust section.
Its primary function is to reduce exhaust restriction after the turbocharger, supporting freer exhaust gas movement towards the remaining exhaust system.
Its main functions and benefits include:
- Improved Exhaust Gas Flow: Replaces the factory catalytic converter with a less restrictive exhaust passage.
- Reduced Exhaust Backpressure: Helps reduce resistance to exhaust gases downstream of the turbocharger.
- Enhanced Turbocharger Sound: Makes turbo spool-up and whistle more noticeable.
- Improved Performance Potential: Reduced exhaust restriction may support improved power delivery under suitable operating conditions.
- Throttle Response Potential: A less restrictive exhaust arrangement may influence turbocharger response, although results depend on the engine and overall configuration.
- Sportier Exhaust Character: Produces a more pronounced turbocharged flat-six exhaust sound.
- Large-Diameter Tubing: Features 3.0-inch (76 mm) exhaust tubing.
- Smooth Exhaust Routing: CNC mandrel-bent construction helps maintain consistent tube geometry through bends.
- Durable Construction: T304L stainless steel provides corrosion resistance and suitability for high exhaust temperatures.
- Competition-Oriented Design: Based on the concept of Porsche factory racing exhaust components.
- Direct Bolt-On Fitment: Uses the original-style mounting arrangement without requiring permanent modification to the vehicle.
- Reversible Installation: Allows the original catalytic converter to be reinstalled when returning the vehicle to its road-approved configuration.
Symptoms Of Wear Or Failure:
The Fabspeed Cat Bypass Pipe is primarily a competition performance upgrade, not a standard maintenance replacement.
However, deterioration of the original catalytic converter or surrounding exhaust components may prompt owners to inspect or repair the existing system.
Common symptoms of catalytic converter or exhaust system problems include:
1. Reduced Engine Performance
A damaged or restricted catalytic converter may create excessive exhaust backpressure, potentially reducing engine performance.
Possible signs include sluggish acceleration, reduced power under load and difficulty maintaining normal performance at higher engine speeds.
2. Restricted Exhaust Flow
A physically damaged or obstructed catalytic converter may prevent exhaust gases from passing through the system normally.
In severe cases, this can affect the performance of a turbocharged engine.
3. Metallic Rattling from the Exhaust
An ageing catalytic converter may develop damaged or loose internal components.
These can produce rattling or metallic noises, particularly during acceleration or changes in engine speed.
4. Visible Corrosion
Older exhaust components may develop rust or corrosion due to moisture, road salt and repeated heating and cooling.
Severe deterioration can weaken pipework, joints and mounting points.
5. Exhaust Leaks
Cracked components, deteriorated gaskets or damaged flange connections may allow exhaust gases to escape.
Symptoms can include unusual blowing noises, increased exhaust volume and escaping fumes.
6. Unusual Exhaust Smells
Changes in exhaust odour may indicate catalytic converter deterioration, an exhaust leak or an underlying engine combustion problem.
The cause should be diagnosed before replacing components.
7. Excessive Exhaust Heat
An internally restricted catalytic converter can contribute to abnormal temperature conditions within the exhaust system.
Severe overheating may damage surrounding components and should be investigated promptly.
8. Damaged Mounting Connections
Corroded fasteners, damaged flanges or deteriorated exhaust mountings may compromise the security of the original catalytic converter.
9. Poor Turbocharger Response
Excessive exhaust restriction can affect turbocharger operating conditions.
However, reduced boost response may also be caused by turbocharger wear, boost leaks, wastegate faults or fuel and ignition problems.
10. Visible Impact Damage
Ground clearance issues, road debris or previous accidents may damage the original catalytic converter or adjacent exhaust pipework.
Why Replacement / Upgrading Matters:
- Maintaining a correctly functioning exhaust system is important for engine performance, turbocharger operation, structural integrity and vehicle safety.
- On the Porsche 964 Turbo and 965, exhaust gases pass through the turbocharger before flowing into the downstream exhaust system.
- The factory catalytic converter reduces harmful exhaust emissions while also forming part of the original exhaust routing.
- In competition applications, a catalytic converter bypass may be used to reduce downstream exhaust restriction where permitted by motorsport regulations.
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.
FSPOR964TCB
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