Fabspeed Muffler Bypass IMSA Zork Tube. Porsche C2 TURBO, 965, 964 Turbo (1990-1994)  ›  FSPOR964TZMB

The Fabspeed Porsche C2 Turbo / 965 / 964 Turbo Muffler Bypass IMSA Zork Tube is a competition-inspired performance exhaust upgrade designed for Porsche 911 Turbo models manufactured between 1990 and 1994.

Fits:

• Porsche 964 (911) TURBO 3.3L 1990-94
• Porsche 964 (911) TURBO 3.6L 1990-94

Developed by Fabspeed Motorsport, this high-flow exhaust component recreates the distinctive short exhaust outlet design associated with the legendary Porsche 934 IMSA and Le Mans racing cars of the late 1970s.

The IMSA Zork Tube replaces the original restrictive rear exhaust arrangement with a short, large-diameter outlet that directs exhaust gases away from the turbocharger with minimal downstream restriction.

Its design is intended to deliver maximum exhaust sound, improved turbocharger response and a dramatic motorsport-inspired driving experience.

Manufactured with 3.0-inch (76 mm) exhaust tubing, the Fabspeed Zork Tube features an integrated angle-cut outlet that can be adjusted to achieve the correct position beneath the rear bumper.

By reducing exhaust restrictions after the turbocharger, this system is designed to improve exhaust gas evacuation and allow the turbocharger to respond more freely.

Fabspeed advertises performance gains of up to 46 wheel horsepower and 65 lb-ft of torque, based on its published testing. Actual results depend on engine condition, vehicle specification, existing modifications and operating conditions.

One of the most distinctive features of this product is its sound. The Zork Tube creates an exceptionally loud, aggressive exhaust character, with pronounced turbocharger whistle, spool-up sounds, crackles, pops and exhaust burbles.

Unlike a conventional sports muffler, the IMSA Zork Tube prioritises exhaust flow and sound over noise reduction.

The direct-fit design uses four mounting nuts at the turbocharger connection and an adjustable slip-joint outlet, allowing straightforward installation on a compatible exhaust configuration.

The Fabspeed IMSA Zork Tube is ideally suited to Porsche 964 Turbo and 965 owners preparing vehicles for track days, motorsport events or dedicated competition use.

What This Product Does:
The Fabspeed IMSA Zork Tube provides a short, high-flow exhaust route from the turbocharger towards the rear of the vehicle.

Instead of passing exhaust gases through the standard rear muffler arrangement, the Zork Tube allows them to exit through a substantially less restrictive pipe.

Its key functions and benefits include:

• Reduced Exhaust Backpressure: Provides a freer-flowing outlet after the turbocharger.
• Improved Exhaust Gas Flow: Uses 3.0-inch (76 mm) tubing to support efficient exhaust evacuation.
• Enhanced Turbocharger Response: Reduced downstream restriction may help the turbocharger build boost more readily.
• Increased Performance Potential: Fabspeed advertises gains of up to 46 wheel horsepower and 65 lb-ft of torque.
• Aggressive Race-Inspired Sound: Produces an extremely loud exhaust note inspired by historic Porsche competition cars.
• Pronounced Turbo Whistle: Makes turbocharger spool-up and operating sounds considerably more noticeable.
• Exhaust Crackles and Pops: Allows more combustion-related exhaust sounds to be heard.
• Direct Exhaust Routing: Minimises the complexity and length of the downstream exhaust path.
• Reduced Exhaust System Weight: Eliminates heavier original exhaust components where replaced by the tube, although Fabspeed does not publish a confirmed weight-saving figure for this product.
• Adjustable Outlet Position: Features an angle-cut outlet with a slip-joint adjustment.
• Motorsport Appearance: Recreates the distinctive short exhaust arrangement associated with Porsche 934 IMSA race cars.
• Straightforward Installation: Designed to attach directly to the compatible turbocharger outlet arrangement.
• Reversible Modification: Allows original components to be retained and refitted when required.

However, owners may consider replacing or refurbishing their original exhaust system when it shows signs of damage or deterioration.

• Older mufflers and exhaust pipes can develop corrosion following prolonged exposure to moisture, road salt and repeated temperature changes.
• Severe corrosion may weaken the exhaust housing, joints and mounting points.
• Cracked pipework, failed gaskets or damaged connections can allow exhaust gases to escape before reaching the intended outlet.
• Symptoms may include blowing noises, increased exhaust volume and visible soot around leaking joints.
• Internal baffles or other components inside an ageing muffler may become loose or damaged.
• This can produce metallic rattling, unusual vibrations or changes in exhaust sound.
• Damaged or obstructed exhaust components may restrict gas flow, increasing exhaust backpressure.
• Severe restriction can affect engine output and turbocharger operating conditions.
• A severely restricted exhaust system may contribute to slower boost response or reduced engine performance.
• However, these symptoms can also result from turbocharger wear, boost leaks, wastegate faults or other engine problems.
• Corroded fasteners, fractured brackets or deteriorated supports may allow unwanted exhaust movement.
• This can produce rattling, vibration or contact with surrounding bodywork.
• Impact damage, crushed sections or deformed pipework can compromise the structural condition of the original exhaust.
• Loose connections or failed supports may allow the exhaust system to move beyond its intended position.
• A leaking exhaust may allow fumes to escape near the engine compartment or vehicle body.
• Exhaust leaks should be investigated promptly because exhaust gases can contain dangerous carbon monoxide.
• Corrosion or deformation around flange connections may prevent the exhaust from sealing correctly.

• Upgrading to the Fabspeed IMSA Zork Tube offers a distinctive motorsport-focused exhaust configuration for Porsche 964 Turbo and 965 models.
• The original Porsche exhaust system was engineered to balance performance, exhaust noise, emissions control and normal road usability.
• For dedicated competition vehicles, a shorter and less restrictive exhaust outlet may provide benefits where motorsport regulations permit its use.