APR 2.5 TFSI Stage III GTX Turbocharger System

APR is pleased to present the TT RS 2.5 TFSI Stage III GTX Turbocharger System!

In the 1980s, an iconic legend was born as the world fell in love with Audi’s 5-cylinder engine’s unmistakable and intoxicating growl. To the Audi enthusiast, the light-weight, compact 5-cylinder engine represented the hallmark of Audi’s technical prowess and ability to emotionally captivate an audience with a driving experience unlike any other in its time. Audi’s announcement of the return of its 5-cylinder roots via the 2.5 TFSI sent shockwaves across the community and resonated deeply within the hearts and minds of APR’s staff. With this creation, Audi spoke directly to every enthusiast and gave APR the unique opportunity to write into Audi’s 5-cylinder history books with modern day engineering expertise.

APR’s technical reach has grown enormously since opening in the 1990s and currently represents a force of unmatched performance without compromise within the performance enhancement sector for Audi vehicles. The APR Stage III 2.5 TFSI Turbocharger System is a culmination of roughly two years worth of engineering research, development and motorsport testing unheard of in the market today. With brutal testing on multiple continents, including wins in the prestigious German Tuner GP at the Hockenheim ring, the APR Stage III Turbocharger System is the pinnacle of Audi’s German engineering enhanced by APR’s American ingenuity.

The APR Stage III Turbocharger System is a turnkey solution designed to expand on the TT RS’s already stellar performance by increasing peak horsepower to roughly double that of the European model. Sitting at 665 horsepower and over 560 ft-lbs of torque on high octane fuel, the vehicle’s performance is transformed to that of a modern day equivalent of Audi’s motorsport 5-cylinder engines of yesteryear. APR’s advanced knowledge of engine management combined with an uncompromising selection of premium materials, access to the latest engineering equipment and techniques, as well as a highly educated and capable staff of engineers, resulted in a turbocharger system capable of delivering a truly exhilarating and fulfilling driving experience. 

Stage III Turbocharger System

APR Switzerland Wins the German Tuner GP at Hockenheim!


APR’s engineering teams use professional grade tools to aid in development of the APR Stage III Turbocharger System. Through the use of coordinate measuring machines, such as the Creaform 3D laser scanner and FaroArm, spatial constraints within the 2.5 TFSI’s engine bay were captured to give APR’s engineers a detailed map of their design environment. The 3D laser scanner allows for quick and easy modeling of static hard parts, such as the turbocharger unit. The modeled parts are placed within the mapped engine bay and development on the system begins using PTE’s Creo 2 3D CAD software. With such an unforgivingly tight working environment, this data is absolutely necessary to ensure every parts fits as intended.

3D Laser Scanning
APR Stage III CREO Renderings
Faroarm Data Collection

Unfortunately an engine bay is not a fixed working environment. Under load the engine mounts allow for movement, ultimately changing and limiting the spatial constraints even further. Before production hardware is created, APR’s engineers print each part using an in house sterolithography 3D printer. Fitment is then tested and necessary changes are made before casting the final pieces.

SLA Creation
SLA Hardening
Finished SLA Piece

Over the entire development period, APR’s Calibration and Electrical Engineering teams continued modifying the factory engine management system to provide a smooth and reliable driving experience. Particular attention was paid towards driving characteristics, ultimately increasing the responsiveness of the entire system through the reduction of turbocharger lag. Given that the system operates at such high levels of performance, it’s often outside of the scope originally intended by the factory ECU. As a result, APR’s Electrical Engineers added patented control strategies to the ECU to enable proper control in all situations.

APR Calibration and Logging suites
APR Sound Master Dyno Cell
APR ECU Coding Suite

Success of the system depended greatly upon the results of APR’s accelerated life testing. APR’s in-house TT RS as well as select APR Importers' vehicles from across the globe were chosen for their locations in harsh environments. From the Swiss Alps to the South African deserts, APR’s engineers spent over a year collecting data through normal daily driving and grueling motorsport events. As new design requirements arose during testing, changes were made and testing continued. The end result is an extremely powerful, yet reliable turbocharger system worthy of APR’s stamp of approval.

Test Vehicle Test Vehicle Test Vehicle Test Vehicle Test Vehicle

More than a year before release, APR gave The Drive Network’s Matt Farah access to the vehicle for early developmental feedback. At the time, the vehicle was producing less power than available today, but still offered a thrilling experience. See what Matt had to say in the video below.

APR Stage III GTX Components

To learn more about each piece of the APR Stage III Turbocharger System for the 2.5 TFSI, please click on the images below for further details.

Turbo CHRA Turbo Compressor Cover Turbo Turbine Cover ECU Upgrade Heat Shielding Exhaust Manifold Wastegate Compressor Inlet Pipe Compressor Outlet Pipe Exhaust Downturn Exhaust Downpipe Oil and Coolant Lines High Pressure Fuel Pump Install Hardware Spark Plugs
Turbo CHRA
Turbo Compressor Cover
Turbo Turbine Cover
ECU Upgrade
Heat Shielding
Exhaust Manifold
Compressor Inlet Pipe
Compressor Outlet Pipe
Exhaust Downturn
Exhaust Downpipe
Oil and Coolant Lines
High Pressure Fuel Pump
Install Hardware
Spark Plugs


At the heart of the APR Stage III GTX Turbocharger System is a GTX3576R turbocharger, utilizing the latest technologies from Le Mans winning turbo manufacturer, Garrett Honeywell. The turbo features a fully-machined, eleven-blade billet compressor wheel and a dual ball bearing oil and water-cooled CHRA. APR’s Engineers spent countless hours testing several turbocharger units to arrive at a configuration suitable for their power, reliability and drivability requirements. Testing began with smaller internally gated units and gradually increased over time until a balance was met within all categories. The result is a system that spools quickly with excellent response, even in the lower RPM range, while producing top end power figures beyond that of a Audi R8 LMS Ultra V10 FSI!

Each turbocharger unit is assembled and clocked in-house at APR with the necessary components to ensure proper fitment and orientation for compressor inlet and outlet systems as well as all oil and coolant lines.

Turbocharger Compressor Cover

The turbocharger is fed through a massive 4-inch ported shroud compressor inlet. This newly developed compressor housing’s anti-surge porting greatly complements the spool characteristics of this unit and grants APR’s Engineers the ability to deliver massive levels of torque inducing boost pressure, even in the lower RPM range. APR’s Engineers enhance the compressor cover by adding an OEM style clampless connection system for the large turbo inlet pipe. This ensures proper orientation of the pipe, ease of installation and a leak free operation.

Turbocharger Turbine Housing

APR’s Engineers tested several turbine-housing designs, both internally and externally gated, with a multitude of inlet and outlet styles as well as A/Rs before arriving at the Tial Sport stainless steel vband .63 A/R turbine housing.

The housing is an investment cast smooth 304L stainless steel design, which offers many benefits over traditional cast iron housings. The design is compact and lightweight, reducing weight by roughly 33% over the typical cast iron counterpart. Furthermore stainless steel features heat retention characteristics, which aid in turbo response by keeping exhaust velocity high. GTVFL3.0 Vband inlet and VBF300M vband outlets completely eliminate the need for exhaust studs, gaskets and bolts to provide a leak-proof sealing surface, all while remaining easy to install.

To aid in reducing temperature under the hood and area surrounding the turbocharger, APR’s Engineers modified the turbine housing with Swain Tech’s ceramic coating. No other ceramic coating on the market comes close to Swain Tech’s proven track record of high mileage, motorsport proven performance and is the industry standard for thermal barriers.

Engine Management

The factory Bosch MED 9 engine management system is responsible for proper operation of the engine in all conditions. With built in compensational data for environmental variables and varying load conditions, the factory ECU is far more complex and intelligent than units found in other vehicle makes and marques.

With the significant amount of changes included in the APR Stage III Turbocharger System, APR’s Engineers spent months calibrating the engine management system to operate smoothly as if intended by the OEM. Thanks to APR’s incredible proprietary calibration suite, data logging software and full access to the coding structure of the ECU, appropriate and intelligent changes are made to ensure flawless drivability and excellent performance without compromise. When necessary, APR’s Electrical Engineers are able to build new coding functions, strategies and routines into the ECU to control conditions normally unseen at factory power levels.

APR’s upcoming EMCS program switching technology puts control of the ECU in your finger tips allowing you to access modes for standard pump fuel, high output race fuel and even reduced output valet modes to protect your vehicle against improper use by other individuals. This technology is patented by APR and is found nowhere else in the world. It’s Performance Without Compromise only APR can deliver!

Heat Shielding

To further combat excessive heat generated by producing power levels seen nowhere else in the industry, APR’s Engineers paid close attention to heat generated by the turbocharger system under prolonged motorsport use. High quality materials are used throughout the system and critical high heat components are coated with Swain Tech’s ceramic thermal barrier.

APR designed and created a proprietary turbo blanket for the 2.5 TFSI Stage III Turbocharger System to provide an additional level of protection a step beyond thermal coatings. A tightly woven fiber consisting of pulverized volcanic rock houses high temperature rated silica to provide a stronger and more durable heat blanket when compared to many off the shelf solutions. The blanket provides an excellent heat barrier designed to protect surrounding components from excessive heat.

FireFlex and DEI heat shrouding sleeves are used throughout the system to protect oil and coolant lines as well as other hoses from surrounding high temperature components. Reflect-A-Gold is utilized on the compressor inlet hose to resist higher intake air temperature and additional material is included to protect surrounding components.

With lower under-hood temperatures, oil and coolant temperatures remain low to protect the engine while intake air remains cooler providing more horsepower, even under extremely demanding situations.

Exhaust Manifold

Exhaust Manifold

Attached to the turbocharger is APR’s investment-cast, super alloy, nickel-chromium-based Inconel 625 Manifold featuring APR’s Sequential Exhaust Pulse runner lengths. Unlike hand welded tubular manifolds, Inconel is a very high temperature resistant material designed to withstand extreme exhaust gas temperature changes without expanding, contracting, melting or cracking under stress. Furthermore, the thick casting material reduces unwanted exhaust noise, leaving behind a powerful and exotic 5-cylinder growl Audi enthusiasts have come to love. This material is typically found only at the highest levels of professional motorsport racing where reliability is essential to success.

To provide smooth and leak-proof operation between the manifold, turbo and external wastegate, APR’s exhaust manifold features Vband connection points. This eliminates the need for exhaust studs, nuts and gaskets and introduces an easier install for the end user while increasing overall reliability.

Investment-cast Inconel features heat retention characteristics, which aid in turbo response by keeping the exhaust velocity high. With exhaust gas pulses occurring 144 degrees apart, APR’s Engineers designed variable runner lengths calibrated to deliver sequential exhaust pulses without collision. This aids in turbocharger spool, producing excellent response for immediate torque delivery. A reduction in backpressure from the high-flow, collision-free design directly enhances power delivery far beyond that of the OEM turbocharger manifold and other less effective designs.  

Each unit undergoes strict quality control checkpoints to ensure ultimate reliability each step of the manufacturing and treatment process. The unit is CNC machined to tight tolerances and inspected for defects before undergoing thermal treatments at Swain Tech. Swain Tech’s world-renowned ceramic material is used to provide a thermal barrier between the manifold and all surrounding components. Through exhausting motorsport-testing APR found this treatment not only necessary for sustained wide-open operation, but also a critical component in reducing intake air temperature for prolonged performance, lap after lap.

The manifold features an EGT bung port for 2.5 TFSI engines featuring an EGT probe and remains capped on models without this OEM component.

All of these characteristics result in a manifold designed without compromise backed by a confidence-inspiring lifetime warranty.



A wastegate is a valve that provides a means for controlling boost pressure on a turbocharged engine. The unit controls the amount of exhaust gasses passing over the turbine wheel as prescribed by APR’s Stage III ECU Software. There are two types of wastegate configurations, internal and external, and each have their own advantages depending on application. With the addition of a massive turbocharger unit, APR’s Engineers found external gating necessary.

APR’s Stage III Turbocharger System features a compact Tial Sport MV-S 38mm external wastegate with water-cooling and vband connection points. The unit is constantly subjected to extreme temperatures and as such features high temperature based materials for increased life and performance. The addition of water-cooling ensures reduced temperatures under extreme motorsport conditions.

Temperature resistant materials are used throughout the unit as evidenced by the 347 stainless steel housing. The wear resistant racing valve is based on NiCrFe alloys and mates to Nitronic 60 stainless steel valve seats and bushings. The valve is actuated by a high heat resistant 17-7 PH stainless steel spring between a Nomex reinforced silicon diaphragm.

APR treats the housing with Swain Tech’s premium ceramic coating to provide a thermal barrier between the wastegate and surrounding components. Each unit’s spring pressure is spec’d and set at APR prior to shipping to provide accurate control. Lastly, each unit is fitted with APR’s flexible braided stainless steel lines for integration into the turbocharger's water-cooling system via the included multi-ply high-temperature-silicone junction point.

Turbocharger Compressor Inlet Pipe

A cast aluminum induction system was created to support the Stage III Turbocharger systems massive airflow requirements without worry of collapsing under extreme conditions. The cast pipe smoothly transitions from the OEM intake connection point down to the turbocharger’s 4-inch inlet where it’s attached via a clampless OEM style connection. This provides leak proof operation and smooth transitional airflow at all junction points while remaining easy to install and maintaining compatible with OEM and upgraded intake systems.

To combat heat soak, neighboring high temperature items feature a Swain Tech ceramic coating while the compressor inlet pipe is wrapped with Reflect-A-Gold at critical points for additional heat protection. Extreme motorsport testing proved the design to be a success, even after hours of continued use.

Turbocharger Compressor Outlet Hose


Wire reinforced, multi-ply silicone hoses provide an unrestricted path for airflow existing the turbocharger. The ultra rigid design ensures piping will not swell or collapse causing leaks and restrictions in the charge piping system. The hose is engineered to fit properly into the engine bay with all necessary ports securely affixed.

APR’s Easy-Flow Silicone Hose design features stepped mounting surfaces for smooth transitions from one pipe to another. Traditional designs simply sit on top of each other, often resulting in a disruptive airflow path. By using the stepped design, hoses fit properly without airflow restrictions, resulting in the most ideal path for moving air through the system.


Turbocharger Exhaust Downturn

An investment cast 3” stainless steel downturn provides a smooth and uninterrupted path for exhaust gases existing the turbocharger at high velocity. Vband clamps make install a cinch, providing a leak proof connection point while removing the need for gaskets, studs and nuts. The high temperature resistant stainless steel design increases the components strength without fear of component failure even under the most grueling environments. A port is provided for the OEM primary oxygen sensor and a second Vband connection links the downturn to the rest of the exhaust downpipe system.

Exhaust Downpipe

APR’s 3-inch T304 stainless steel downpipe connects seamlessly to the supplied downturn and is fully compatible with APR’s RSC turboback exhaust system, full downpipe, or midpipe exhaust system. Vband clamps make install a cinch, providing a leak proof connection point while removing the need for gaskets, studs and nuts. The wastegate exhaust piping is fed back into the primary exhaust system far away from the turbine as to not disrupt flow.

Turbocharger Oil and Coolant Lines

APR’s oil and coolant lines are specific to the APR Stage III Turbocharger System and provide years of leak free operation. The lines feature a flexible braided stainless steel construction with CNC mandrel bent hard-lines for specific and clean routing as if intended by the OEM. FireFlex and DEI heat shrouding sleeves (not pictured above) protect the lines from surrounding high temperature components and reduce oil and coolant temperatures typically seen under extreme conditions. A multi-ply silicon junction point provides a means for neatly connecting coolant lines to the factory system. Every detail is important, and APR goes the extra mile to ensure any possible weaknesses are eliminated.

High Pressure Fuel Pump


Sold separately as a brand new pump or rebuild of the engine’s existing pump, the APR High Pressure Fuel Pump addresses fueling needs and leaves plenty of headroom for safety and further increased power levels in the future. By increasing the pump’s internal capacity, the fueling system is capable of displacing a higher volume of fuel per minute at every RPM. Read More on our High Pressure Fuel Pump Product Page.


Install Hardware

APR doesn’t cut corners even with the most mundane details of the kit. Every nut, bolt, washer, clamp and gasket necessary for the install is included with the kit.

Spark Plugs

Included with each kit are five Denso Iridium IKH24 (5346) spark plugs designed to operate properly and resist knock under the extreme cylinder pressures produced in the APR Stage III Turbocharger System.

APR Stage III GTX ECU Upgrade Calibration Report
As Rated
by Audi
Stock 93 AKI
As Measured
by APR
91 AKI
95 RON

93 AKI
98 RON

100 AKI
104 RON

104 AKI
108 RON

AKI - Anti Knock Index or (RON+MON)/2 for Octane Ratings  |  RON - Research Octane Number for Octane Ratings | North American Model
Rev Limiter 6,800 RPM 6,800 RPM 7,300 RPM 7,300 RPM 7,300 RPM 7,300 RPM
Speed Limiter Limited Limited Unlimited Unlimited Unlimited Unlimited
Peak Mechanical Horsepower (HP) 335 - 355 HP 374 HP 518 HP 553 HP 665 HP TBD
Peak Torque (FT-LBS) 332 - 342 TQ 361TQ 484 TQ 526 TQ 561 TQ TBD
Max Horsepower Gain over Stock (HP @ RPM)     +138 @ HP 6,750 RPM +182 @ HP 6,750 RPM +283 HP @ 6,750 RPM TBD
Max Peak Torque Gain over Stock (FT-LBS @ RPM)     +137 TQ @ 4,500 RPM +180 TQ @ 4,600 RPM +236 TQ @ 6,200 RPM TBD

Acceleration Testing

Acceleration Data
Vehicle Stage Transmission 60-120 MPH 62-124 MPH 100-200 KPH 60-130 MPH 30-130 MPH
Stage III PBox acceleration data collected on the same day and same stretch of airport runway at full vehicle weight with ESP enabled.
Stock 6 Speed Manual 11.20 sec - - 14.90 sec 17.70 sec
APR Stage III - 93 Octane Mode 6 Speed Manual 6.89 sec 7.39 sec 7.43 sec 8.94 sec 11.00 sec
APR Stage III - 100 Octane Mode 6 Speed Manual 6.04 sec 6.46 sec 6.49 sec 7.80 sec 9.75 sec
APR Stage III GTX Turbocharger Systems
Vehicles Transmission System Part Price(税別)
Existing APR software customers will receive a fully loaded ECU when it becomes available. New customers will receive one program and may purchase additional programs à la carte. Please check for EMCS availability.
Audi TT RS 6 Speed Manual APR Stage III GTX Turbocharger System - Includes Software T3100050 ¥2,400,000
Audi TT RS S-Tronic (DSG) APR Stage III GTX Turbocharger System - Includes Software To Be Announced

Stage III GTX Required Components and Recommendations (Sold Separately)

APR High Pressure Fuel Pump


The APR HPFP expands the 2.5 TFSI’s direct injection fueling capabilities to the levels required for proper operation with the APR Stage III Turbocharger System. The pump is offered in two forms. A entirely new pump can be purchased, or the vehicle's existing pump can be sent to APR for a rebuild.

APR Exhaust Midpipe

APR Midpipe

The APR Midpipe Exhaust System connects the included exhaust downturn and downpipe to the factory catback exhaust system or APR RSC Catback Exhaust System. This part is only necessary if the vehicle is not currently equipped with an APR Downpipe Exhaust System or APR RSC Turboback Exhaust System.

APR Intercooler System

APR Intercooler

The APR Intercooler System is a necessary upgrade for the system to run safely and to meet the advertised power levels. The factory intercooler shows signs of weakness on a completely stock 2.5 TFSI and as such is not capable of supporting the APR Stage III Turbocharger System's power levels.

  • Exhaust: APR recommends the APR RSC Catback Exhaust System.
  • Intake: APR recommends a high flow intake filter.
  • Clutch: An upgraded clutch is necessary for manual transmission vehicles, such as the Sachs Clutch System.
  • Internals: APR recommends upgraded connecting rods when running race fuel calibration modes for increased reliability.
  • Replacement Install Hardware: APR and Audi recommend replacing one time use bolts during the install.
  • Fluids and Lubricants: APR recommends Motul Fluids and Lubricants.

APR Tuned

Phone: (092) 883-9222 Fax: (092) 883-9213 Address: 1-18-3-101, Ikinomatsubara, Nishi-ku, Fukuoka, 819-0055

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