Audi A4 B9 Downpipes – Catted & Decat Performance Exhaust Upgrades

Audi A4 B9 Downpipes – Unlock the Full Potential of Your Turbocharged Engine

The Audi A4 B9, produced from 2016 onwards, represents the fifth generation of Audi’s popular mid-size sedan and estate lineup. Featuring advanced technology, improved chassis dynamics and a wide range of efficient TFSI and TDI engines, the B9 platform is highly tunable. However, the restrictive OEM downpipes limit performance and sound. Upgrading to a performance Audi A4 B9 downpipe is one of the most effective modifications to increase power, improve turbo response and enhance exhaust acoustics.

Why Upgrade to a Performance Audi A4 B9 Downpipe?

The factory downpipe is designed to comply with emissions and noise regulations, but this significantly restricts exhaust flow and reduces turbocharger efficiency. A performance downpipe delivers:

• Higher horsepower and torque – optimized exhaust flow allows your turbo to breathe freely and generate more power.
• Faster turbo spool – reduced lag means sharper throttle response and quicker acceleration.
• Improved exhaust sound – catted downpipes offer a refined, sporty tone, while decat downpipes unleash a louder, motorsport-inspired roar.
• Lower exhaust gas temperatures – improved thermal efficiency increases reliability and protects components under high loads.
• Perfect for ECU tuning – an essential upgrade for Stage 1, Stage 2 and hybrid turbo builds.

Types of Audi A4 B9 Downpipes

We offer a full range of Audi A4 B9 downpipes designed for various driving styles and performance goals:

Catted Audi A4 B9 Downpipes

Catted downpipes use a high-flow sports catalytic converter to improve exhaust flow while maintaining emissions compliance. Perfect for daily-driven B9s in regions with strict testing.

Decat Audi A4 B9 Downpipes

Decat downpipes remove the catalytic converter entirely, providing maximum exhaust flow and peak performance. Ideal for track builds, off-road applications or areas without emissions restrictions.

Stainless Steel & Titanium Audi A4 B9 Downpipes

Material quality directly affects durability, performance and weight:

• Stainless steel downpipes – the most popular option, corrosion-resistant, strong and cost-effective.
• Titanium downpipes – ultra-lightweight, excellent heat resistance and a premium motorsport-grade finish.

Engine Compatibility

Our Audi A4 B9 downpipes are engineered to fit a wide range of petrol and diesel engines, including:

• Audi A4 B9 2.0 TFSI Downpipes – optimized for Stage 1 and Stage 2 power upgrades.
• Audi A4 B9 3.0 TFSI Downpipes – designed for the high-performance V6 petrol engines.
• Audi A4 B9 2.0 TDI Downpipes – improve torque and efficiency on diesel builds.
• Audi A4 B9 3.0 TDI Downpipes – high-flow options for powerful V6 diesel models.
• Audi S4 B9 Downpipes – performance upgrades for the quattro-equipped 3.0 TFSI V6.

Performance Gains with Audi A4 B9 Downpipes

Installing a performance Audi A4 B9 downpipe provides immediate benefits. Typical gains include:

• +20–35 HP with the downpipe alone.
• +40–70 HP when paired with Stage 2 ECU remapping.
• Improved torque delivery throughout the rev range.
• Sharper throttle response and reduced turbo lag.

Choosing the Right Diameter

Selecting the right exhaust diameter ensures optimal performance gains. Common sizes for Audi A4 B9 downpipes include:

• 2.5-inch downpipes – perfect for Stage 1 tunes and lightly modified setups.
• 3-inch downpipes – ideal for Stage 2 builds, hybrid turbos and high-boost applications.

All our downpipes are designed for direct bolt-on installation, ensuring seamless fitment with OEM and aftermarket exhaust systems.

Build Quality & Engineering

Our performance Audi A4 B9 downpipes are built to withstand extreme conditions and deliver maximum gains. Key features include:

• Mandrel-bent tubing for smooth, unrestricted exhaust flow.
• High-grade stainless steel or lightweight titanium construction.
• Precision TIG welding for strength and durability.
• OEM-style flanges and fittings for leak-free installation and perfect fitment.

Tuning Potential

Pairing a performance Audi A4 B9 downpipe with ECU remapping unlocks the full potential of your engine:

• Substantial horsepower and torque improvements.
• Optimized turbo response and fueling strategies.
• Sharper throttle response and smoother power delivery.
• Custom exhaust sound profiles based on catted or decat configurations.

Daily Driving vs Track Builds

For street-driven vehicles, catted downpipes provide a perfect balance between emissions compliance and power gains. For track-oriented builds, decat downpipes offer unrestricted flow, maximum power and an authentic motorsport tone.

Conclusion

Upgrading to a performance Audi A4 B9 downpipe is one of the most effective ways to enhance your vehicle’s power, responsiveness and exhaust sound. Whether you choose a catted downpipe for street use or a decat downpipe for ultimate performance, our range of Audi A4 B9 downpipes ensures premium build quality, seamless fitment and proven results. Unlock your B9’s full tuning potential today.