APR DPK0019 Cast Downpipe for Audi (B8/8.5) 2.0T A4, A5, allroad, and Q5

Posted on July 27, 2016 – 12:00 pm

APR is pleased to present the ultimate Cast Downpipe Exhaust System for Audi’s (B8/8.5) A4, A5, allroad, and Q5!

Product Page

The APR Cast Downpipe Exhaust System replaces the restrictive factory downpipe and chambered resonator with a larger, 76mm stainless steel mandrel-bent system, featuring a bell-mouth cast inlet, high-flow catalyst and various other features. Expect better throttle response, more horsepower and an intoxicating exhaust note, while remaining civilized during normal daily driving. It’s one of the best performance upgrade for the 1.8 TFSI and 2.0 TFSI following the APR ECU Upgrade and it’s all designed and assembled in-house, using premium materials and world-class manufacturing techniques few can match.

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Quick Facts

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More power and less turbo lag
+40-47 HP & +36-45 FT-LBS over APR Stage I (B8 A4 2.0T).

Full 76mm downpipe system
Say goodbye to the tiny, kinked, 60mm tubing and chambered resonator.

Bell-mouth investment-cast downpipe inlets
Ultra smooth cast inlet for unmatched performance.

GESI High-flow catalysts
Strong and reliable catalyst, with reduced emissions, smell and noise over catless setups without the performance hit.

T304L stainless steel construction
Premium grade materials to resists corrosion and stands the test of time.

Argon back-purged TIG welding
Clean, strong and attractive welds both inside and outside the pipes.

OEM-style low-profile slip-on clamps
Easy to install with tons of clearance. Resists leaks and doesn’t deform the pipe.

OEM-style internally-corrugated flex section
High flow without the failures common with braided setups.

Investment cast secondary oxygen sensor bungs
A perfect fit that doesn’t protrude into the pipe.

Compatible with the OEM catback exhaust
Bolt-on and go.

In-house design, assembly and quality control
All critical aspects of the system are handled internally to ensure the highest quality fit and finish.

All hardware and instructions included
All included for a headache free install.

APR Stage II ECU Upgrade price waived
Upgrade from APR Stage I to APR Stage II for free.

Limited lifetime warranty
The best system with the best warranty.

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Cast Downpipe

The downpipe is like nothing else on the market. The investment-cast, bell-mouth inlet provides an ultra smooth transition between the turbo’s 80mm outlet and the high quality catalyst’s inlet. All of the tubing in the system is upgraded from the awkwardly-kinked, 60mm tubing to attractively-brushed, straight-through and mandrel-bent 76mm tubing. The CNC laser cut bracket provides a strong and accurately positioned mounting point to take the weight of the downpipe off the turbocharger, and the internally-corrugated flex section gives the downpipe the flex it needs under engine movement. Finally, the downpipe uses T304L stainless steel components that are TIG welded together with argon back-purging, ensuring the system not only looks great on the inside and out, but stands the test of time.

76mm Midpipe

The APR Cast Downpipe Exhaust System is a “full” downpipe, as it also includes the midpipe section underneath the vehicle. The factory midpipe uses awkwardly-kinked, 60mm tubing with some systems featuring a chambered resonator that poses a large restriction, especially vehicles with upgraded turbochargers. The APR midpipe eliminates the front resonator, giving the exhaust a slightly more aggressive note, while eliminating performance robbing restrictions. Finally, the midpipe uses attractively-brushed, straight-through and mandrel-bent 76mm T304L stainless steel tubing.

Flex Section

The APR midpipe use an OEM-style flex section that is fully sealed with a corrugated inner lining to improve flow and reliability. The low profile design and minimal use of braiding material eliminates clearance issues common with other designs that can billow, rub, rattle and fray over time. The flex section is constructed from T304L stainless steel and is argon back-purged when TIG welded to the downpipe.

Catalytic Converter

APR’s engineers specified a high-quality and high-flow GESI metal 300-cell catalyst ideal for forced induction application. During dyno testing, the 100mm x 100mm design showed no measurable loss in power, thanks to the catalyst’s design.

Internally the catalytic converter feature a proprietary wash coat that helps to reduce emissions and smell common on cat-less setups. The low-profile catalyst features a fully captured substrate brick, which is furnace braised to the outer mantle and physically captured by the diffuser cones preventing rattling, rotation, and damage to the substrate. Subsequently, a byproduct of running the catalyst is a reduction in noise, making the system as a whole more pleasing to the ear.


Attached to the downpipe is a high quality mounting bracket. The bracket is constructed from T304L stainless steel and is CNC-machined and CNC-bent to exact tolerances. The bracket is TIG welded to the piping and argon back-purged.


APR’s engineers specified a T304L stainless steel, OEM-style exhaust clamp designed to eliminate the need for flanges, swedging, or slip fittings. By using this low profile design, the exhaust system can be positioned higher in the exhaust tunnel and away from the ground with better clearances compared to flanged setups. Each clamp allows for less turbulence and greater accuracy at the connection points as the pipes simply butt up to one another rather than the ambiguity and voids associated with swedged slip fittings. Furthermore, the clamp doesn’t rely on deforming the pipe to provide a tight seal, making install and removal more convenient.

Oxygen Sensor Bung

APR’s Engineers paid special attention to the details when designing the APR Cast Downpipe Exhaust System all the way down to the oxygen sensor bung. APR’s O2 bung is investment cast from T304L stainless steel and is curved to perfectly fit on the catalyst, without protruding into the pipe, as this would further impede airflow beyond the sensor itself. The bung is TIG welded to the piping and argon back-purging is used to ensure the interior surface is smooth and clean.


A simple and removable, T304L stainless steel reducer, featuring a smooth transition, is included, making the APR Cast Downpipe Exhaust System directly compatible with the OEM catback exhaust system.


Included with each system is an OEM gasket, designed to mate between the downpipe and the turbocharger.

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Dyno Testing

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B8 A4 2.0T – APR Stage II – 287 HP & 341 FT-LBS – +47 HP @ 6,700 RPM & +45 TQ @ 3,100 RPM Over APR Stage I – 91 Octane
B8 A4 2.0T – APR Stage II – 291 HP & 354 FT-LBS – +40 HP @ 6,700 RPM & +36 TQ @ 3,150 RPM Over APR Stage I – 93 Octane

Reported wheel figures measured using APR’s AWD Dynapack with multiple vehicles, using SAE correction and an average of multiple runs for all figures. Stage II included a high flow downpipe. Crank figures are estimated based on the measured wheel figures. Results may vary depending upon environmental conditions, vehicle, transmission, vehicle health, operating conditions, temperatures, fuel grade, dyno type, dyno setup, other variables and other modifications.

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The APR Difference

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The Engineering and Designing Phase

In the past APR worked with other manufacturers to develop a limited range of private-label exhaust systems outside the scope of APR’s internal development and manufacturing capabilities. Understanding the limits of such a program, combined with APR’s desire to deliver higher-quality products in a timely manner with better customer support, APR invested in internalizing the program. With the release of this exhaust system and the others like it, APR is pleased to present their first systems fully designed and engineered in-house from the ground up!

Design and development begins with the use of APR’s professional grade in-house coordinate measuring machines. APR’s engineers have full access to a Romer Absolute arm with integrated laser scanner, FaroArm and Creaform 3D laser scanner for collection of special constraints surrounding the factory exhaust system. The engineers scan the vehicles and create detailed 3D maps of their design environment while designing each system in PTC Creo 3.0 CAD software.

Using APR’s in-house stereo-lithography 3D printer, rapid prototypes are created for fitment on the vehicle. The design is easily and quickly verified, and if necessary, changes can be made. Once adequate clearances and fitment is confirmed, especially in areas that move under load, physical quick-cast prototypes are created and fitted for final verification through real-world use.

APR’s world-class manufacturing partners from around the globe are responsible for manufacturing each component that falls outside of APR’s internal capabilities. Working closely with each manufacturer, APR’s engineers supply CAD models, materials specs, and other design specifications and work hand-in-hand with the manufacturer to develop the components. The end result is a collection of components, wholly unique to the APR name, awaiting final finishing, assembly and quality control at APR’s 78,000 square foot facility in Opelika, Alabama in the USA.

The Fabrication, Finishing and Assembly Phase

Manufacturing takes place both internally and externally to APR while finishing and assembly is completed in-house. APR’s fabrication team sends each cast component through the ceramic vibrating tumblers to smooth and de-burr surface imperfections. Each component is then cleaned by hand and prepared for assembly.

APR’s fabrication experts TIG weld each component, creating reliable, high quality and attractive welds. Each component is back-purged with argon during the process ensuring the weld is strong and consistent, as well as clean throughout. With this process complete, the APR Cast Downpipe Exhaust System is born!

Final Quality Control

APR has placed a large emphasis on improving quality control across various product lines, and the exhaust program is not excluded. To ensure the systems are delivered as advertised, APR’s engineers have taken a multi-step approach that encompasses many techniques that go beyond the industry standard.

Metallurgy Testing
APR’s engineers request full metallurgy reports with each batch of components to ensure the components are made with the material grades specified on the original design prints. This information is then cross-referenced against randomly selected and independently tested samples before the components are released for assembly.

Dimensional Inspection
Great designs only matter if the manufacturer delivers the components as expected. To help ensure the designs are as specified, APR’s engineers randomly select components and conduct full dimensional inspections using in-house 3D laser scanning equipment. Tolerances are digitally checked against the original specifications and passed or failed based on the results.

Operating in an environment designed for accuracy and repeat-ability, APR’s fabrication experts leave little room for error during the final assembly phase. Jigs and fixtures, created in-house, live on custom-specified fabrication tables. This working environment ensures the highest level of quality control during the assembly process and safeguards against dimensional variations potentially created during the manufacturing process. The end result is a system that fits every time as it’s true to the original design specifications.

Visual Quality
When hand-building the products in-house, an extra level of control takes place. Components are visually checked for imperfections, and items that fall out of quality standards are rejected. The products are then packaged with care before being distributed across the world.

APR’s confidence in the system’s quality allows for a limited lifetime warranty.

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Application Guide

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Audi A4 (8K – B8 & B8.5)
Audi A5 (8T – B8 & B8.5)
Audi Q5 (8R)

1.8 TFSI EA888 Gen 1
2.0 TFSI EA888 Gen 2

Quattro – Left Hand Drive

Part Number


Stage 2 Software
Free upgrade from APR Stage 1 with purchase of APR downpipe, or +$149.99 upgrade from APR Stage 1 with a different downpipe.

– Pricing: Please contact an APR Importer for pricing outside the USA.
– Availability and ECU Compatibility: Stages, programs, and features may not be available for all ECUs.
– ECU Revision Notice: Multiple ECU revisions exist for each platform. APR software may be temporarily unavailable when factory updates are applied. An APR dealer can check availability in person, or over the phone if the ECU boxcode/revision is known.
– Stage II Pricing: Customers who have purchased an APR ECU Upgrade before February 16th, 2015 are exempt from upgrade fees.