Catless Turbo 3" to 2.5" Downpipe Exhaust for 1997-2005 Audi S4 B5 A6 Allroad C5 2.7L K03 K04 RS6

SKU: XKV21074
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Fitment & Specs
Fits selected manual-transmission Audi B5/C5 2.7L V6 30V turbo applications: 2000–2002 B5 S4, 2000–2004 C5 A6 Quattro, and 2001–2005 C5 Allroad Quattro. Verify turbo flange, O2 sensor layout, and downstream exhaust connection.
3" Inlet · 2.25" Outlet
T304 Stainless Steel · Vehicle-Specific Downpipe Set · Professional Install Recommended
Before You Buy: Off-road/racing use only · Professional install recommended · May Be Required Depending on Setup
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Description

This catless turbo downpipe set is designed for selected Audi B5 S4 and C5 A6 / Allroad 2.7T manual-transmission applications, including the 2000–2002 Audi S4 B5, 2000–2004 Audi A6 Quattro C5, and 2001–2005 Audi Allroad Quattro C5.

Built from T304 stainless steel with mandrel-bent 3" piping tapering to 2.5", flex sections, V-band style connections, and CNC-machined flange sections, the system uses a 3" inlet and 2.25" outlet as listed. It is designed for compatible K03, K04, and RS6-style turbo flange configurations where the required connection and exhaust layout match the vehicle.

CORE FITMENT B5 S4 / C5 A6 & Allroad

Selected Audi 2.7T manual-transmission applications.

PRODUCT TYPE Catless Downpipe Set

Twin-downpipe configuration for the Audi 2.7T turbo exhaust layout.

PIPE DESIGN 3" → 2.5" Tapered

3" inlet with listed 2.25" downstream outlet connection.

Important — Manual Transmission & Turbo Configuration

This downpipe set is listed for manual-transmission applications only. K03, K04, and RS6-style references describe compatible turbo / flange configurations and do not mean that this product fits every Audi model associated with those turbo names.

Product Overview

This product is a vehicle-specific catless turbo downpipe set for compatible Audi B5 / C5 2.7L V6 30V BiTurbo applications. It connects the turbo outlet area to the downstream exhaust system and is intended for the listed chassis, engine, transmission, and turbo flange configurations.

It is not a turbo kit, header set, catback system, complete exhaust system, or universal exhaust pipe kit.

Key Details

Product Type Catless Turbo Downpipe Set
Engine 2.7L V6 30V BiTurbo
Core Platforms Audi B5 / C5
Transmission Manual Only
Pipe Design 3" Tapering to 2.5"
Inlet Size 3"
Outlet Size 2.25"
Material T304 Stainless Steel
Wall Thickness 16 Gauge / 1.5 mm
Flex Sections Integrated
Turbo Compatibility K03 / K04 / RS6-Style
Configuration Twin Downpipe Set

Vehicle Fitment

Use the table below to confirm the main listed applications. Fitment should be verified by exact model year, B5 / C5 chassis, 2.7T engine, manual transmission, turbo flange configuration, O2 sensor layout, and downstream exhaust connection.

Vehicle Year Engine Fitment Notes
Audi S4 B5 2000–2002 2.7L V6 30V BiTurbo Core application · Manual transmission only · Verify turbo flange and O2 sensor layout
Audi A6 Quattro C5 2000–2004 2.7L V6 30V BiTurbo Core application · Manual transmission only · Verify turbo and downstream exhaust configuration
Audi Allroad Quattro C5 2001–2005 2.7L V6 30V BiTurbo Core application · Manual transmission only · Verify turbo and downstream exhaust configuration
Audi RS4 B5 Additional Fitment 2002 2.7L V6 30V BiTurbo Verify exact vehicle, turbo setup, flange connection, and exhaust configuration before ordering
Fitment Note: This downpipe set is designed for the listed Audi B5 / C5 2.7T applications and is listed for manual transmissions only. Confirm the exact vehicle, transmission, turbo flange, O2 sensor layout, downstream exhaust connection, and installation clearance before purchase.
What Does K03 / K04 / RS6-Style Fitment Mean?

These references describe compatible turbo-side flange and connection layouts, not separate vehicle applications.

K03 Factory-style 2.7T turbo configuration where the listed flange matches.
K04 Upgraded turbo configuration using the compatible listed connection.
RS6-Style RS6-style turbo / flange configuration — not Audi C5 RS6 vehicle fitment.

Pipe & Connection Details

Turbo-Side Inlet 3"
Pipe Layout 3" Tapering to 2.5"
Outlet Connection 2.25"
Turbo Connection K03 / K04 / RS6-Style Hybrid Flange Configuration
Construction T304 Stainless Steel · Mandrel Bent · Welded
Flex Sections Integrated

Package Includes

  • Catless turbo downpipe set as shown
  • Upper and lower downpipe sections as supplied
  • V-band connection components included with the supplied kit
  • Gaskets / installation hardware only where included with the supplied package

Please compare the received components with the product photos before installation. If you need confirmation of the exact clamps, gaskets, or hardware included, contact us before ordering.

Installation Notes

BEFORE INSTALLATION Confirm Vehicle & Turbo Configuration
  • Verify B5 / C5 chassis and 2.7T engine.
  • Confirm manual transmission.
  • Compare turbo-side flange layout with your existing setup.
  • Verify O2 sensor positions and downstream exhaust connection.
DURING INSTALLATION Check Alignment & Clearance
  • Professional installation is strongly recommended.
  • Test fit all sections before final tightening.
  • Check clearance around the transmission, driveshaft, heat shields and subframe.
  • Keep O2 wiring and surrounding components clear of hot exhaust surfaces.

Modified turbo setups or non-original downstream exhaust systems may require adjustment or fabrication. Compatible tuning, calibration, or sensor-related solutions may also be required depending on the vehicle and O2 sensor configuration.

Inspect all connections for exhaust leaks after installation and recheck clamps and fasteners after initial heat cycles where appropriate.

BEFORE YOU BUY
Confirm the B5 / C5 2.7T Setup Before Ordering
  • Designed for the listed Audi B5 S4 and C5 A6 / Allroad 2.7T manual-transmission applications.
  • This is a catless turbo downpipe set, not a turbo kit, header set, catback system, complete exhaust, or universal pipe kit.
  • The 3" to 2.5" specification describes the tapered pipe layout; the listed downstream outlet connection is 2.25".
  • K03, K04, and RS6-style references describe compatible turbo / flange configurations, not unrelated Audi vehicle fitment.
  • Verify exact model year, chassis, 2.7T engine, manual transmission, turbo flange, O2 sensor layout, downstream exhaust connection, and installation clearance before purchase.
  • This product does not include catalytic converters and may alter emissions-related exhaust components.
  • Compatible tuning, calibration, or sensor-related solutions may be required depending on the vehicle setup.
  • Intended for off-road, racing, competition, or closed-course use where emissions laws apply. Check applicable regulations before installation.
Shipping & Return

SHIPPING & DELIVERY
Fast Processing & Reliable Transit

  • Processing: Orders are processed and shipped from the nearest available warehouse within 1 business day after payment.
  • Delivery: Estimated delivery time is approximately 3–4 business days after shipment.
  • Shipping - Free shipping on all orders within the contiguous 48 U.S. states.

RETURNS & EXCHANGES
30-Day Hassle-Free Policy

  • Return Window: We offer a 30-day return policy from the date of delivery.
  • Item Condition: Returned items should be unused, uninstalled, and in their original packaging when possible.
  • Return Process: To initiate a return or exchange, please contact our customer service team first to receive authorization and instructions.

WARRANTY
2-Year Limited Replacement Warranty

  • Duration: All products are backed by a 2-year limited warranty.
  • Coverage: This warranty covers manufacturing defects and product failures under normal use, and provides a replacement for qualified cases (repairs are not performed).

CUSTOMER SUPPORT
We’re Here to Help – Contact Us First

  • Priority Contact: For any order-related issues—including returns, warranty claims, or general inquiries—please contact us first before taking further action. We are committed to resolving your concern promptly.
  • Feedback Notice: If you are unsatisfied, we kindly ask that you allow us an opportunity to address the issue before leaving neutral or negative feedback.
  • Email Support: You can reach us at support@XKVracing.com.

Downpipe Buying Guide

A Key Section in a Turbocharged Exhaust System

The downpipe connects directly to the turbocharger and routes exhaust gases into the rest of the exhaust system. It is one of the first exhaust components downstream of the turbo.

Because of its position, the design of the downpipe influences how exhaust gases move away from the turbo and into the remaining exhaust path.

What Drivers May Observe

More consistent exhaust flow downstream of the turbocharger

Reduced restriction compared to some factory exhaust layouts

Smoother boost delivery under certain operating conditions

Changes in exhaust tone, depending on system setup

Catted vs Catless

Catted Downpipe

Includes a catalytic converter designed for specific applications
Used where emissions considerations or regulations apply
Often selected for vehicles intended for street use, where permitted

Catless Downpipe

Does not include a catalytic converter
Typically intended for off-road, competition, or export use
Used in applications where different regulatory standards apply

Is a Downpipe Right for Your Build?

Own a turbocharged vehicle

Are upgrading intake, intercooler, or exhaust components

Want improved exhaust efficiency and response

Are building a balanced street or track setup

FAST SHIPPING

Ships within 1 business day after payment
3–4 business day delivery

Secure and Reliable Checkout

Secure checkout with major payment options

LOCAL WAREHOUSE

Orders ship from U.S. warehouses when available

Easy Returns and Exchanges

30-day returns for eligible unused items

Parts Warranty

Warranty support for qualified manufacturing defects

Important Notice

Products on this site are intended for off-road, racing, or closed-course use where emissions laws apply. They are not represented as street legal, emissions-compliant, or legal for use on public roads unless explicitly stated.

Some products may remove, replace, relocate, disable, or alter emissions-related components, including but not limited to catalytic converters, EGR, DPF, SCR, DOC, O2 sensors, or related factory systems. Compatible tuning, calibration, or supporting modifications may be required to avoid engine codes or drivability issues.

Professional installation is recommended. Buyers are responsible for verifying product compatibility, local regulations, emissions requirements, and any required tuning or supporting modifications before purchase and installation.

Performance gains, sound changes, airflow improvements, temperature changes, fuel economy changes, fitment, and drivability results may vary. No specific performance gains are guaranteed.

Downpipe FAQs

What is a downpipe? +

A downpipe is the exhaust section that connects to the turbocharger and routes exhaust gases toward the rest of the exhaust system. Depending on the vehicle and product design, an upgraded downpipe may help reduce exhaust restriction and support improved turbo response when paired with the right setup.

What's the difference between catted and catless downpipes? +

A catted downpipe includes a catalytic converter, while a catless or racing downpipe does not include one and may alter or remove emissions-related equipment. Catless or racing downpipes are generally intended for off-road, racing, or closed-course use where emissions laws apply. Always check the product details and local regulations before purchase.

Will a downpipe increase horsepower? +

A downpipe may support improved exhaust flow and power potential when combined with proper tuning and supporting modifications. Horsepower and torque gains are not guaranteed and will vary depending on the vehicle, engine condition, tune, fuel, turbo setup, and overall exhaust system.

Do downpipes make the vehicle louder? +

A downpipe can change exhaust tone and may increase turbo or exhaust sound depending on the vehicle, whether the downpipe is catted or catless, and the rest of the exhaust system. Final sound level varies by setup.

Do I need tuning after installing a downpipe? +

Tuning requirements depend on the vehicle, downpipe design, emissions equipment, O2 sensor setup, and supporting modifications. Some applications may require compatible tuning or calibration to support drivability and reduce the chance of warning lights or engine codes.

Will a downpipe trigger a check engine light? +

It may, depending on the vehicle, catalytic converter configuration, O2 sensor location, and ECU calibration. Catless or racing downpipes are more likely to require supporting calibration or sensor-related solutions. Always verify the product notes and tuning requirements before installation.

Are downpipes street legal? +

Street legality depends on the downpipe design, emissions equipment, vehicle application, and local regulations. Catless, racing, or emissions-altering downpipes are generally intended for off-road, racing, or closed-course use where emissions laws apply and are not represented as street legal unless explicitly stated.

Can I use a downpipe with my stock exhaust system? +

Compatibility with a stock exhaust system depends on the vehicle and the specific downpipe design. Some downpipes are designed to connect to factory-style exhaust sections, while others may require compatible aftermarket exhaust parts, adapters, clamps, gaskets, or fabrication. Always check the product fitment and installation notes before ordering.

Are downpipes hard to install? +

Installation difficulty varies by vehicle. Some applications require tight access around the turbocharger, O2 sensors, heat shields, transmission area, or underbody. Rusted factory hardware and limited clearance can also increase installation difficulty. Professional installation is recommended.

Will a downpipe affect reliability? +

Reliability depends on product fitment, installation quality, tuning or calibration, heat management, sensor placement, gasket sealing, fastener condition, and the vehicle’s overall condition. Incorrect installation or mismatched tuning may cause drivability issues.

What should I verify before buying a downpipe? +

Verify your year, make, model, engine, turbo setup, emissions configuration, catalytic converter requirements, O2 sensor layout, flange or clamp connection, exhaust compatibility, and any tuning or calibration needs before purchase.