APR Cast Downpipe Exhaust System for the 4.0 TFSI

+25-59 Horsepower

+32-95 FT-LBS of Torque

Cast Bell Mouth Inlets

Full 76mm Stainless Steel System

APR is pleased to present the ultimate Cast Downpipe Exhaust System!

The APR Cast Downpipe Exhaust System replaces the restrictive factory catalyst cross pipes and resonators with an upgraded 76mm stainless steel mandrel-bent system, featuring port-matched cast inlets, high-flow catalysts and various other features. Expect better throttle response, more horsepower and an intoxicating exhaust note, while remaining civilized during normal daily driving. It’s the best performance upgrade for the 4.0 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:

  • More power and better response
    Expect a decrease in turbo lag with power and torque gains as high as 59 HP and 95 FT-LBS of torque over APR Stage I!
  • Full 76mm downpipe system
    The APR system is a full downpipe upgrade as it replaces the kinked 60mm catalyst cross pipes and resonated midpipes with straight through, 76mm mandrel-bent tubing.
  • Port-matched investment-cast downpipe inlets
    The factory inlets are restrictive. APR’s cast system allows for massive, port-matched inlets that smoothly neck down over a long distance. The result is improved flow, better response and more power.
  • Dual, high-flow catalysts
    GESI’s encapsulated catalysts are known for their strength and performance. Expect lower emissions, reduced noise and less exhaust smell compared to catless setups, all without negatively impacting performance to over 1,000 HP. Furthermore, with the catalyst moved, expect a cooler engine bay!
  • T304L stainless steel construction
    Premium grade T304L stainless steel 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
    The APR slip-clamps are easy to use, resist leaks and pipe deformation better than swedged setup, are lower profile than vbands and flanges and don’t require replacement gaskets.
  • OEM-style internally-corrugated flex sections
    APR’s flex sections are internally corrugated to increase flow and prevent failures common with braided flex sections.
  • Investment cast secondary oxygen sensor bungs
    APR’s obsession to details resulted in investment cast oxygen sensor bungs that sit on top of the piping, preventing material from protruding into the exhaust stream, disrupting flow.
  • Compatible with the OEM catback exhaust
    Bolt-on and go! The system is fully compatible with the factory catback exhaust.
  • Designed, assembled and quality controlled in-house
    All critical aspects of the system are handled internally to ensure the highest quality fit and finish.
  • All hardware and instructions included
    New OEM gaskets, oxygen sensor harnesses, clamps, brackets and install instructions are included to make the install as headache free as possible.
  • APR Stage II ECU Upgrade price waived
    With every APR downpipe purchase comes a free upgrade to Stage II from Stage I, saving consumers hundreds of dollars!
  • Limited lifetime warranty
    The best system on the market also carry the best warranty in the industry!

Components

Cast Downpipes Inlets with 76mm Tubing

downpipe downpipe downpipe downpipe

The factory downpipes are less than desirable from a performance standpoint. Both pipes quickly neck down from the massive turbocharger outlet to small and resistive 60mm pipes that are kinked in many areas before twisting and dumping into catalytic converters. APR greatly improved upon this design through the use of investment-cast and port-matched downpipe inlets. Each pipe gradually reduces to the larger and straighter 76mm piping, with the hot catalyst moved further down the exhaust stream to keep under hood temperature down. The photos below show illustrate the differences between the factory and APR exhaust system inlets.

downpipe downpipe downpipe downpipe

The cast inlets, piping and other components are made from the the high-nickel content, premium-grade stainless steel known as T304L. This material was chosen for its excellent corrosion resistance, strength and appearance. The castings are tumbled to smooth and de-burr any imperfections, and all piping is brushed clean before entering the CNC controlled mandrel benders. TIG welding is used at all connection points, and was chosen for its strength and appearance. Each weld is argon back purged during assembly to increase strength and consistency of the welds. The gusseted brackets are CNC laser cut and bent to provide strong mounting points to the factory mounting hardware.   

brackets downpipe downpipe downpipe
 

76mm Midpipes with Catalyst

midpipes midpipes

The APR midpipes replace the kinked factory 60mm resonator pipes with new, 76mm mandrel-bent T304L stainless tubing, complete with OEM style low-profile flex sections, GESI catalysts, investment cast O2 sensor bungs, and reducers. The pipes mate perfectly to the factory catback exhaust system without any modification necessary. All connection points use APR’s OEM style slip clamps providing the ultimate in compatibility, performance and easy of install compared to flanges, v-bands and pipe deforming sedges and slip fits common on other systems.

flex sections catalysts reducers
 

Flex Sections

flex section flex sections

The APR midpipes use OEM-style flex sections that are fully sealed with a corrugated inner lining to improve flow and reliability. The low profile design and minimal use of bradding material eliminates clearance issues common with other designs that can billow, rub, rattle and fray over time. Each flex section is constructed from T304L stainless steel.

 

Catalytic Converters

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

catalysts catalysts

Internally the catalytic converters feature a proprietary wash coat that helps to reduce emissions and smell common on cat-less setups. With performance in mind, the catalysts are placed far away from the turbo outlets to reduce turbulence in the downpipes and to help reduce under-hood temperature. The low-profile catalysts feature fully captured substrate bricks, which are furnace braised to the outer mantles and physically captured by the diffuser cones preventing rattling, rotation, and damage to the substrate. Subsequently, a byproduct of running the catalysts are a reduction in noise, making the system as a whole more pleasing to the ear.

 

Clamps

Clamp

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 Bungs

Bungs

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 bungs. APR’s O2 bungs are investment cast from T304L stainless steel and are curved to perfectly fit on 76mm piping, without protruding into the pipe, as this would further impede airflow beyond the sensor itself. The bungs are TIG welded to the piping and back-purging is used to ensure the interior surface is smooth and clean.

 

Oxygen Sensor Harness

Harness

Two high quality oxygen sensor extension harness are included as the catalysts and sensor bungs are relocated further away from the turbochargers.

 

Gaskets

Harness

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

 
Dyno Testing
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APR Stage II Calibration Report
Vehicle Fuel Max HP Max TQ Max HP Gain
Over APR Stage I
Max TQ Gain
Over APR Stage I
- APR recommends and tuned with Sunoco GT 260 for 100 AKI mode and Sunoco GT 260 Plus for 104 AKI mode. Never use lower octane than specified by the mode.
- Max increases are based on APR's actual measured stock values and not those reported by VAG. | RON = ROW Fuel Grades | AKI = North American (RON+MON)/2 Fuel Grades.
- Reported wheel figures measured using APR's AWD Dynapack and APR UK's AWD Dynojet dyno 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.
Audi S6/S7 (C7) 95 RON 575 HP 669 FT-LBS +56 HP @ 3,850 RPM +82 TQ @ 3,350 RPM
Audi S6/S7 (C7) 98 RON 586 HP 694 FT-LBS +52 HP @ 3,950 RPM +73 TQ @ 3,500 RPM
Audi S6/S7 (C7) 104 RON 602 HP 713 FT-LBS +59 HP @ 4,050 RPM +83 TQ @ 3,500 RPM
Audi S6/S7 (C7) 108 RON 614 HP 717 FT-LBS +71 HP @ 4,250 RPM +91 TQ @ 4,000 RPM
 
Audi S6/S7 (C7.5) 95 RON 567 HP 648 FT-LBS +35 HP @ 3,950 RPM +61 TQ @ 2,400 RPM
Audi S6/S7 (C7.5) 98 RON 588 HP 684 FT-LBS +36 HP @ 3,850 RPM +58 TQ @ 2,300 RPM
Audi S6/S7 (C7.5) 104 RON 613 HP 689 FT-LBS +25 HP @ 4,300 RPM +50 TQ @ 2,350 RPM
 
Audi RS6/RS7 (C7) 95 RON 679 HP 703 FT-LBS +40 HP @ 4,950 RPM +74 TQ @ 2,450 RPM
Audi RS6/RS7 (C7) 98 RON 712 HP 751 FT-LBS +44 HP @ 5,050 RPM +77 TQ @ 2,500 RPM
Audi RS6/RS7 (C7) 104 RON 761 HP 793 FT-LBS +43 HP @ 4,700 RPM +85 TQ @ 2,500 RPM
 
Audi RS6/RS7 (C7.5) 95 RON 687 HP 777 FT-LBS +42 HP @ 2,700 RPM +83 TQ @ 2.600 RPM
Audi RS6/RS7 (C7.5) 98 RON 709 HP 797 FT-LBS +42 HP @ 2,700 RPM +83 TQ @ 2,600 RPM
Audi RS6/RS7 (C7.5) 104 RON 730 HP 811 FT-LBS +49 HP @ 4,950 RPM +94 TQ @ 2,650 RPM
Audi RS6/RS7 (C7.5) 108 RON 759 HP 889 FT-LBS +49 HP @ 2,750 RPM +95 TQ @ 2,650 RPM
 
Audi S8 95 RON 672 HP 691 FT-LBS +30 HP @ 4,700 RPM +36 TQ @ 4,100 RPM
Audi S8 98 RON 688 HP 727 FT-LBS +28 HP @ 4,750 RPM +32 TQ @ 4.500 RPM
Audi S8 104 RON 710 HP 751 FT-LBS +32 HP @ 4,200 RPM +41 TQ @ 4,100 RPM

The APR Difference

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 our first systems fully designed and engineered in-house from the ground up!

Romer. CAD SLA

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 stereolithography 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.

Welding Welding Welding

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.

Jig Scanning

Metallurgy Testing

APR’s engineers request full metallurgy reports with each batch of components to ensure the components are made with the T304L stainless steel 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.

Fixtures

Operating in an environment designed for accuracy and repeatability, 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.

Videos

Application Guide
Vehicle Engine Drivetrain Part Number Price Exc. VAT Price Inc. VAT  
Designed for Left Hand Drive (LHD) vehicles only. Right Hand Drive (RHD) vehicles require slight clearancing.
Audi S6 (C7 & C7.5) 4.0 TFSI Quattro DPK0014 £1885.00 £2262.00
Audi S7 (C7 & C7.5) 4.0 TFSI Quattro DPK0014 £1885.00 £2262.00
Audi RS6 (C7 & C7.5) 4.0 TFSI Quattro DPK0014 £1885.00 £2262.00
Audi RS7 (C7 & C7.5) 4.0 TFSI Quattro DPK0014 £1885.00 £2262.00
Audi S8 (D4 & D4.5) - *Requires the S8 adapter 4.0 TFSI Quattro - LHD DPK0014 £1885.00 £2262.00
System

S8 Adapter

The Audi S8’s factory catback exhaust system is located in a slightly different location compared to other models. As such, the APR S8 Adapter is required for proper fitment with the factory catback exhaust. The fit kit consists of two OEM clamps and extension pipes. The system bolts directly between the APR downpipes and factory catback pipes.

Application Guide
Vehicle Engine Drivetrain Part Number Price  
Audi S8 (D4 & D4.5) 4.0 TFSI Quattro FIT0003Locate an APR Importer

For the best results, APR recommends installing the APR Stage II ECU Upgrade. The upgrade price is waived for APR Stage I ECU Upgrade customers with purchase of the APR downpipes.

Stage II ECU Upgrade Pricing
Engine Retail Price Price with Purchase of the APR Cast Downpipe Exhaust System
IMPORTANT PRICING AND AVAILABILITY DETAILS:
- 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.
Audi S6 / S7 (C7 / C7.5) Contact a dealer Free!
Audi A8 / A8L (D4 / D4.5) In Development
Audi S8 (D4 / D4.5) Contact a dealer Free!
Audi RS6 / RS7 (C7 / C7.5) Contact a dealer Free!

APR Tuned

Phone: 0333 240 6823 Address: APR Tuning UK, Unit 1 Siemens Road, Manchester M44 5AH, UK

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While we try to keep everything current, APR tuning Ltd is not responsible for errors in pricing on this web site. All prices are in GBP and are applicable to the UK only.