Porsche GT3 vs. GT4 RS Exhaust: Valvetronic Sound and Dyno Test
The Porsche 992.1 GT3 and 718 GT4 RS share a 9,000-rpm naturally aspirated flat-six, but their rear-engine and mid-engine layouts give them very different exhaust configurations and driving personalities. To compare them, Kies Motorsports tested both cars on the same in-house dyno, installed platform-specific Valvetronic titanium systems, recorded the sound, and returned to the dyno.
The result was not as simple as choosing the car with the highest peak number. Both systems changed the sound, and the dyno plots showed meaningful gains within the rev range even where peak power changed very little.
Hear both Porsches and see the dyno results
Open the full video on YouTube →Featured products
- Valvetronic Valved Sport Exhaust System for Porsche 992 GT3/RS
- Valvetronic Valved Sport Exhaust System for Porsche 718 GT4 RS/Spyder RS
- Kies Motorsports Dyno Services
Always confirm exact model-year fitment, selected options, local sound regulations, and current manufacturer instructions before ordering or installing an exhaust system.
Step 1: Establish Stock Dyno Baselines
The team completed three back-to-back baseline pulls with each car and selected the middle run for the comparison.
| Vehicle | Stock wheel horsepower | Stock wheel torque |
|---|---|---|
| Porsche 992.1 GT3 | 494 whp | 346 lb-ft |
| Porsche 718 GT4 RS | 483 whp | 350 lb-ft |
The stock results were close. The GT3 recorded 11 more wheel horsepower, while the GT4 RS recorded 4 more lb-ft of wheel torque in this test.
These are results from two specific vehicles on one dyno. Fuel, temperature, tire setup, dyno configuration, vehicle condition, and run selection can all affect the numbers, so they should not be treated as guaranteed output for every GT3 or GT4 RS.
Step 2: Install the GT4 RS Titanium Exhaust
The GT4 RS received a Valvetronic titanium system configured with the main muffler, included tips, and over-axle pipes. Because the GT4 RS is mid-engined, its routing differs from the GT3 system even though the cars use closely related engines.
The video presents this portion as an installation overview rather than a bolt-by-bolt service manual. Professional installation is the safest choice when the installer is not fully comfortable with exhaust alignment, fastener torque, heat management, and post-installation inspection.
Step 3: Install the GT3 Titanium Exhaust and Headers
The GT3 received its platform-specific Valvetronic titanium exhaust along with a full header replacement. Its rear-engine layout calls for a different system architecture than the GT4 RS.
That configuration difference matters when interpreting the final comparison. This was a real-world test of the selected packages—not a controlled experiment in which both vehicles received mechanically identical changes.
Step 4: Compare the Sound
Both cars produced a more aggressive exhaust note after installation. Bryan leaned toward the GT3’s sound, potentially because that car also received headers, while noting that the GT4 RS creates a distinctive cabin experience with the engine and intake directly behind the occupants.
Sound preference is subjective. Headphones or phone speakers also cannot reproduce the actual volume and frequency balance of either vehicle. Local noise rules and track sound limits should be checked before selecting a louder configuration.
Step 5: Review the Post-Install Dyno Results
Porsche 992.1 GT3
At peak, the GT3’s recorded result was approximately 2 horsepower lower and 9 lb-ft of torque higher after the Valvetronic installation. That peak-only comparison does not show the full change.
Around 4,500 rpm, the video reports gains of approximately 30 wheel horsepower and 30 lb-ft of wheel torque, with the exhaust-equipped run staying stronger through much of the usable rev range. Bryan also noted that one post-install run ended slightly before 9,000 rpm, which makes the peak-power comparison less conclusive.
Porsche 718 GT4 RS
The GT4 RS increased from 483 to 493 peak wheel horsepower, a 10-whp gain in this test, while peak torque remained near 350 lb-ft. Around 4,800 rpm, the video reports an improvement of approximately 23 wheel horsepower and 25 lb-ft of wheel torque.
Head-to-Head Result
When the final curves were overlaid, the GT3 produced more horsepower and torque once engine speed climbed past roughly 4,200 rpm. Around 4,500 rpm, the GT3 was approximately 22 wheel horsepower and 25 lb-ft ahead of the GT4 RS in the displayed comparison.
That made the GT3 the video’s overall dyno winner. It does not mean the GT3 system will always produce larger gains, because the two cars started with different baselines and received different exhaust configurations.
Key Takeaways
- The stock GT3 and GT4 RS baselines were separated by only 11 whp and 4 lb-ft in this test.
- The GT4 RS posted the clearer peak gain, increasing by 10 whp.
- The GT3 showed its more important improvement in the mid-to-upper rev range rather than at the single peak number.
- The GT3 and GT4 RS use different exhaust layouts, so the required parts are not interchangeable.
- Sound is subjective, and the GT3’s added headers influenced this specific comparison.
- Dyno curves across the usable rev range can reveal changes that a single peak number misses.
Which Valvetronic System Fits Your Porsche?
Choose the product page that matches the vehicle platform, then verify the exact year, model, and desired configuration before ordering:
- Shop the Porsche 992 GT3/RS Valvetronic exhaust
- Shop the Porsche 718 GT4 RS/Spyder RS Valvetronic exhaust
Performance and sound results vary by vehicle, configuration, fuel, conditions, and measurement method. This article summarizes the featured Kies Motorsports test and does not replace current manufacturer installation instructions.