Description
Unlock the performance potential of your Audi A3/S3 8V and Volkswagen Golf R Mk7/Mk7.5 2.0T EA888 Gen 3 with the Untd. Performance 4″ Catless Downpipe, engineered for maximum exhaust flow and designed specifically for serious performance builds.
The downpipe starts with a massive 4″ diameter section at the turbocharger and transitions into a full 3.5″ midpipe, creating an exceptionally high-flow exhaust path from the turbocharger through the mid-section of the exhaust system. This oversized configuration reduces exhaust backpressure, improves turbocharger flow, and provides the capacity needed for higher-boost and upgraded-turbo applications.
Key Features
- 4″ Turbo Outlet: Starts with a massive 4″ diameter section at the turbocharger to maximize exhaust-flow capacity where it matters most.
- 4″ to Full 3.5″ Transition: The system transitions from the 4″ downpipe into a full 3.5″ midpipe, maintaining a large-diameter, high-flow exhaust path.
- Catless Design – Maximum Exhaust Flow: Eliminates the factory catalytic converter to significantly reduce exhaust restriction and backpressure.
- Designed for Serious Performance Builds: The oversized 4″/3.5″ configuration is recommended for serious tuned, high-boost, and upgraded-turbo EA888 Gen 3 setups where maximum exhaust flow is a priority.
- Improved Turbo Response: Reduced exhaust backpressure can help the turbocharger spool more efficiently and improve overall response.
- High-Flow 3.5″ Midpipe: Provides substantial exhaust-flow capacity downstream of the turbocharger while maintaining a properly sized system.
- Aggressive Exhaust Sound: The catless configuration produces a louder, more aggressive exhaust note with increased turbocharger and exhaust character.
- Installation Hardware Included: Includes the required installation hardware for mounting the downpipe and midpipe to the vehicle.
- Built for High-Output Applications: Ideal for vehicles running upgraded turbochargers, higher boost, and supporting performance modifications.
4″ Downpipe → 3.5″ Midpipe Flow Design
The defining feature of this system is its 4″ to 3.5″ stepped exhaust design.
The exhaust begins with a 4″ diameter section directly from the turbocharger, providing maximum available flow area immediately after the turbine. It then transitions into a full 3.5″ midpipe, maintaining an extremely high-flow exhaust path through the rest of the assembly.
4″ Turbo Outlet → 3.5″ Midpipe → Rest of Exhaust System
This design makes the system particularly well suited to serious performance builds, where the additional exhaust-flow capacity of a large-diameter downpipe can become increasingly important.
Recommended for Serious Setups
While the system can provide benefits on a mildly tuned vehicle, the 4″ downpipe and full 3.5″ midpipe are especially recommended for serious EA888 Gen 3 builds.
This includes:
- High-boost Stage 2 setups
- Hybrid turbo builds
- Big-turbo applications
- High-power Golf R builds
- High-power S3 builds
- Vehicles targeting substantially higher-than-stock power
- Builds where exhaust backpressure is a major consideration
For a stock-turbo daily driver, a smaller high-flow system may be sufficient. The Untd. Performance 4″/3.5″ system is designed for enthusiasts who are building toward serious power and maximum exhaust-flow capability.
Estimated Performance Gain
The additional exhaust flow can reduce backpressure and improve turbocharger efficiency. The factory ECU may not fully utilize the additional flow, while an appropriate ECU calibration can unlock substantially more of the available performance.
| Configuration | Estimated HP Gain | Estimated Torque Gain | Estimated Output |
|---|---|---|---|
| Stock Tune | +5–12 HP | +5–12 lb-ft | Approximately 310–327 HP* |
| Stage 1 | +45–65 HP | +50–75 lb-ft | Approximately 350–370 HP* |
| Stage 2 | +65–90 HP | +65–100 lb-ft | Approximately 370–395 HP* |
| Upgraded Turbo | +80–120+ HP | +80–130+ lb-ft | Build dependent |
*Estimates use a 300–315 HP reference range representative of certain Golf R/S3 configurations. Actual factory output varies by vehicle, model year, market, and engine calibration.
These are general crankshaft estimates. Actual results depend on fuel quality, ECU calibration, turbocharger, ambient temperature, and supporting modifications.
Stage 1 vs. Stage 2
Stage 1:
The 4″/3.5″ exhaust system can be installed with a Stage 1 calibration and provides improved exhaust flow and turbocharger response. However, the calibration may not be specifically optimized around the additional flow capacity.
Stage 2:
A compatible Stage 2 ECU calibration can take greater advantage of the high-flow 4″ downpipe and 3.5″ midpipe, allowing increased boost and optimized ignition and fueling strategies.
For upgraded-turbo applications, the additional exhaust-flow capacity becomes even more relevant as the turbocharger moves significantly greater volumes of exhaust gas.
⚠️ Check Engine Light Warning
Because this is a catless downpipe, removing the factory catalytic converter can trigger a Check Engine Light related to catalyst efficiency and rear-O2 sensor readings.
A compatible ECU calibration is strongly recommended for optimal performance. Catalyst-efficiency and rear-O2 monitoring may need to be addressed by the calibration where legally permitted.
Installation Hardware Included
The Untd. Performance 4″ Catless Downpipe includes the required installation hardware to facilitate installation on the specified applications.
The system is designed as a performance-oriented replacement for the factory downpipe and midpipe assembly. Professional installation is recommended to ensure proper fitment, alignment, and sealing of all connections.
Why Upgrade?
The factory exhaust system is designed around OEM power levels, emissions requirements, and everyday drivability. As boost and engine output increase, exhaust restriction becomes increasingly important.
The Untd. Performance system addresses this with a 4″ turbo outlet transitioning into a full 3.5″ midpipe, creating a substantially larger flow path than the factory system.
The result is reduced exhaust backpressure, improved turbocharger response, increased flow capacity, and significantly greater supporting capability for serious tuned and upgraded-turbo EA888 Gen 3 builds.
Compatibility
Audi
- A3 8V 2.0T EA888 Gen 3
- S3 8V 2.0T EA888 Gen 3
Volkswagen
- Golf R Mk7 2.0T EA888 Gen 3
- Golf R Mk7.5 2.0T EA888 Gen 3
Important: This product is intended for compatible EA888 Gen 3 applications. It is not intended for the later EA888 EVO4/Mk8 platform.
Recommended Supporting Modifications
For a serious EA888 Gen 3 performance setup, pair the 4″/3.5″ exhaust system with:
- ECU Stage 2 or custom calibration
- Upgraded intercooler
- High-flow intake
- Turbo inlet
- Upgraded charge pipe
- DSG/TCU calibration
- Hybrid or big-turbo upgrade
- Upgraded fueling system where required
- Additional engine and drivetrain cooling
⚠️ Important Notice
CATLESS — OFF-ROAD / CLOSED-COURSE USE ONLY.
This product removes the factory catalytic converter and is intended for closed-course, competition, or other lawful off-road applications. It is not legal for public-road use where catalytic converters and emissions-control equipment are required.
A Check Engine Light may occur after installation. Professional installation and appropriate tuning are recommended.
Horsepower and torque figures are estimates and will vary based on vehicle configuration, ECU calibration, fuel quality, environmental conditions, turbocharger, and supporting modifications.
Reviews
There are no reviews yet.