Why Upgrade to a Tubi Exhaust on Your Cayman GT4?

The Porsche Cayman GT4 is already a track-focused masterpiece, but upgrading its exhaust system can transform the driving experience. A Tubi Style exhaust is renowned for its handcrafted Italian engineering, T304 stainless steel construction, and a signature sound that’s both refined and aggressive. Beyond the auditory thrill, a Tubi system shaves significant weight off the rear of the car, reduces backpressure, and can unlock subtle horsepower gains when paired with a proper tune. For GT4 owners who want a more visceral connection to the engine, installing a Tubi exhaust is one of the most rewarding modifications. This guide walks you through the entire process, from tools to final test drive, with pro tips to ensure a flawless fit and long-lasting performance.

Before diving into installation, understand that the Tubi Style exhaust for the 981 and 718 GT4 models typically replaces the factory rear mufflers and connecting pipes. It’s a direct bolt-on system, but attention to detail – especially with hanger alignment and torque specs – separates a perfect installation from a rattly one. Check Tubi’s official site for the exact part number that matches your model year. We’ll cover both the 981 (2016–2019) and 718 (2020+) GT4 installations, noting any differences when applicable.

Tools and Materials Needed

Having the right gear on hand prevents frustration and damage to expensive parts. Below is a comprehensive list, along with why each item matters.

  • Socket set (metric, ½-inch drive) – You’ll need 10mm, 13mm, 15mm, and 18mm sockets for manifold nuts, hanger bolts, and clamp bolts.
  • Torque wrench (ft-lb and in-lb ranges) – Crucial for tightening header-to-muffler bolts to factory specs (typically 22–25 ft-lb for the exhaust flanges, 15 ft-lb for hanger brackets).
  • Jack (low-profile) and four jack stands – A high-quality jack gives you the clearance needed to slide the entire exhaust out from under the car. Use stands rated for at least 3 tons.
  • Ratchet with extensions (6” and 12”) – Extensions help reach bolts tucked behind the rear bumper and heat shields.
  • Cutting tool (reciprocating saw with metal blade or exhaust pipe cutter) – Only needed if you plan to remove a section of the stock exhaust permanently (many aftermarket kits come with full replacement pipes). Have it ready just in case.
  • Tubi Style exhaust system – Ensure it includes all required pipes, mufflers, clamps, and hardware. Lay everything out to verify.
  • New exhaust gaskets (metal crush or multi-layer steel) – The thickness and material are critical to seal against exhaust pulses. Purchase OEM‑spec replacement gaskets compatible with GT4 headers.
  • Penetrating oil (PB Blaster or equivalent) – Apply to nuts and bolts 24 hours before installation to ease removal of corroded hardware.
  • Rubber mallet – Gently tap stubborn hanger bushings without damaging the aluminum chassis.
  • Safety glasses and mechanic’s gloves – Protect your eyes from falling debris and hands from sharp edges and heat.
  • Shop rags and a flashlight – Clean work area improves visibility and prevents dirt from entering exposed exhaust ports.

Preparation: Setting Up for a Clean Installation

A well-prepared workspace reduces installation time and risk of mistakes. Follow these steps before raising the vehicle.

Safety and Vehicle Prep

Park the Cayman GT4 on a flat, level concrete floor. Engage the parking brake (even though you’ll be on stands) and chock the front wheels. Allow the engine and exhaust to cool completely – at least one hour after driving. Hot components can cause severe burns and make gaskets and bolts more prone to stripping. Wear safety glasses throughout the process; fragments from broken bolts or rusted clamps can fly unexpectedly.

Workspace Organization

Lay out the new Tubi exhaust components on a clean tarp or cardboard. Compare each piece to the factory parts to confirm correct orientation. The Tubi system’s polished tips should align with the GT4’s rear diffuser cutouts. Inspect the supplied hardware: you should receive stainless steel bolts, spring-loaded washers, and rubber hangers. If any are missing, contact your supplier before proceeding.

Undercarriage Inspection

With the car on the ground, crawl underneath and spray penetrating oil on every exhaust-related bolt, especially the flange nuts at the primary catalytic converters and the rubber hanger posts. This is particularly important if your GT4 has lived in a salt‑belt region. Let the oil soak for at least 30 minutes before you start turning wrenches.

Step-by-Step Installation

Step 1: Raise the Cayman GT4 Securely

Position the jack under the rear jacking point (the reinforced area behind the front wheels). Lift the car until the rear wheels are about 6 inches off the ground, then place jack stands under the designated lift points on the chassis rails. Lower the car onto the stands gently. Repeat on the front if you prefer a level working angle, but raising only the rear is sufficient for exhaust removal. Shake the car to ensure stability before sliding underneath.

Step 2: Remove the Stock Exhaust System

Start at the rear. Use a 13mm socket to unbolt the two muffler tips from the bumper (they often have small screws on the bottom). Then disconnect the oxygen sensor wiring clips – these are usually located near the catalytic converters. Carefully unclip them; do not pull on the wires themselves.

Next, support the rear muffler section with a jack (or a helper) to relieve tension on the rubber hangers. Use a 15mm socket to remove the four bolts connecting the muffler pipes to the secondary cats. If the bolts are seized, apply additional penetrating oil and give them a few sharp taps with a hammer to break the corrosion. Slide the muffler off the rubber hangers using a pry bar if necessary – the rubber is tough, but be gentle to avoid tearing.

With the mufflers free, move forward to disconnect the center section (if your stock system has one). Loosen the pipe clamps and separate the sections. A reciprocating saw with a metal‑cutting blade can be used to cut through stubborn pipes, but avoid cutting into chassis components or fuel lines. Remove all factory pipes and set them aside. Inspect the hanger brackets; if they look rusted, replace them with new stainless steel units.

Step 3: Inspect and Prep the Tubi Exhaust Components

Open the Tubi box and compare each pipe to the removed stock parts. The Tubi system is engineered for a direct fit, but sometimes the hanger positions can be slightly off – especially on earlier 981 cars. Use a file to lightly deburr any weld slag on the pipe ends that could prevent a perfect seal. Install the supplied rubber hangers onto the brackets. Apply a thin coat of anti‑seize compound to the flange studs to prevent future corrosion. Replace the exhaust gaskets at every joint – do not reuse old gaskets, as they will leak after being compressed.

Step 4: Install the New Tubi Exhaust

Begin assembly from the front of the car. Attach the Tubi downpipes or primary pipes to the headers using the new gaskets and your torque wrench set to 22–25 ft‑lb. Use a crisscross pattern to ensure even clamping. Then, move rearward, connecting the secondary pipes to the muffler section. Slide each rubber hanger over the chassis posts – a squirt of dish soap on the hanger rubbers eases this step. Use the rubber mallet to seat stubborn hangers.

Once all components are loosely bolted together (all hardware snug but not yet torqued), align the exhaust tips in the rear bumper cutouts. Rotate the tips until they are perfectly centered and equally protruding. Then, tighten all clamp bolts and hanger nuts to the final torque. Double‑check that no part of the exhaust contacts the chassis, driveshaft, or heat shields – any vibration point will cause a drone or rattle.

Step 5: Torque All Bolts to Specification

Using your torque wrench, recheck every fastening point. Exhaust flanges: 22–25 ft‑lb. Clamps: 30–35 ft‑lb (or as indicated on the clamp). Hanger bracket nuts: 15 ft‑lb. Over‑torquing can strip threads on the aluminum chassis brackets, so use caution. A torque wrench in the inch‑pound range (180–200 in‑lb) is ideal for smaller hardware.

Post-Installation Checks

Before dropping the car, perform a thorough visual inspection. Crank the engine (if safe with the car raised) and listen for immediate leaks. A puff of smoke or a sharp hissing sound indicates a poor seal. Use a soap‑and‑water spray bottle on every joint – bubbles will pinpoint leaks. Tighten the offending connection and retest.

Step 6: Lower the Vehicle and Test for Clearance

Remove the jack stands and lower the car. Cycle the steering lock to lock to ensure the exhaust does not contact the axle half‑shafts. Bounce the rear suspension a few times to settle the car, then recheck the tip alignment. Often the weight of the car changes the exhaust position slightly.

Step 7: Start the Engine and Listen Critically

Start the GT4 and let it idle for three minutes. The Tubi exhaust will have a break‑in period; initially the sound may be raspy or have metallic overtones. This will mellow as the packing material seats. Listen for contact with the chassis (a metallic ringing) or a persistent rattle. If you hear anything concerning, shut off the engine and investigate the clearance.

Step 8: Test Drive

Take the car for a gentle 15‑minute drive, avoiding hard acceleration. The goal is to heat‑cycle the system and allow gaskets to conform. After the drive, park on a flat surface and inspect for any leaks or loose hardware. Re‑tighten the clamps if necessary – they often settle after the first heat cycle. On the second drive, gradually increase engine load to 5,000 rpm. The Tubi exhaust will produce a deep, exotic note; if you hear a rasp above 4,000 rpm, the system may benefit from tighter joints or additional support brackets.

Tips for Longevity and Peak Performance

  • Break‑in period matters. Avoid sustained high rpm for the first 200 miles. The muffler packing needs time to settle, and the stainless steel pipes will develop a slight coloration from heat.
  • Monitor for leaks at every oil change. Loose clamps are the most common issue after installation. Re‑torque them annually.
  • Consider a tune. While the Tubi exhaust works on a stock ECU, a performance calibration (like those discussed on Rennlist GT4 forums) can optimize fuel trims and ignition timing to fully exploit the reduced backpressure.
  • Clean the tips regularly. Use a mild chrome polish to maintain the finish. Avoid acidic wheel cleaners that can etch stainless steel.
  • Inspect hanger rubber annually. Exposure to road salt and heat hardens rubber, leading to vibration. Replace with genuine Tubi hangers for the best fit.

For a visual reference, watch a detailed installation walkthrough on a 718 GT4 – the process is nearly identical to the 981, though the 718 has an additional resonator that simplifies removal.

Common Pitfalls and How to Avoid Them

Even experienced DIYers can run into trouble. Here are the top three mistakes:

  1. Forcing hangers onto misaligned posts. If the rubber bushing won’t slide on, do not use a hammer on the hanger bracket. Instead, loosen all exhaust clamps and shift the pipe assembly 5–10 mm rearward.
  2. Over‑torquing flange nuts. The GT4’s studs are M8 and strip easily. Use a torque wrench – never guess.
  3. Ignoring tip clearance with the rear bumper. The Tubi tips are larger than stock; if they contact the diffuser, the heat can melt the plastic. Leave at least 1/4” (6 mm) gap all around.

What Makes Tubi Different? A Quick Look at the Engineering

Unlike mass‑produced exhausts, each Tubi system is hand‑welded in Italy using T304L stainless steel. The wall thickness is 1.5 mm – lighter than the factory 2.0 mm but still durable enough for track use. The internal baffles are tuned to produce a specific sound frequency; for the GT4, it emphasizes the flat‑six’s guttural midrange without overwhelming drone at highway speeds. The entire system weighs approximately 25–30 pounds less than the OEM setup, which is a noticeable unsprung weight reduction. When combined with a lightweight battery, this can sharpen turn‑in response.

Conclusion

Installing a Tubi exhaust on your Porsche Cayman GT4 is a weekend project that delivers immediate reward every time you start the engine. By following this step‑by‑step guide, paying close attention to torque specs and hanger alignment, you’ll achieve a professional‑grade fit that lasts for years. The sound, weight savings, and subtle power gains make it one of the best modifications for both street and track use. For additional technical support, refer to Tubi’s official technical page or join the community on enthusiast forums. Enjoy the new voice of your GT4 – it’s a sound that never gets old.