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4.0L TFSI EA825 RS6 / RSQ8 ECU Tune
Purchase 4.0L TFSI EA825 RS6 / RSQ8 ECU Tune
  • SKU: 05-408-00166-0

    4.0L TFSI EA825 RS6 / RSQ8 ECU Tune

  • Advertised gains are estimates of HP and Torque “at the engine” calculated from gains as measured on a Dynojet Dynamometer in ideal conditions and typically show the largest possible change.  Actual gains are dependent on the following: Learn More about Crank HP Vs Wheel HP

    Model – Manufacturers use the same engine in multiple model vehicles and often times they are in a different state of tune, for example: 2008 C63 and a 2008 CLK Black Series.  Both have the same engine, but the C63 has 451hp while the CLK63 has 500hp.  Naturally the C63 will show more gains as it starts at a lower level.

    Model Year – Similar to above, as time progresses, Manufacturers tend to slightly increase power output via software from one year to the next or offer “Performance Packages” with increased power.  The engines remain largely unaltered and as a result, final tuned output remains the same, while the gains are lower as the starting point is now higher.

    Fuel – Fuel quality is HIGHLY important with performance vehicles.  Low quality and/or low octane fuel will greatly impact engine output and potentially even engine health.  Top tier brand premium fuels should always be used to achieve the best results possible.

    Drivetrain – All wheel drive has higher drivetrain losses than rear wheel drive.  This results in lower numbers when testing on a chassis dyno.  Wheel/tire size and weight will also impact chassis dyno results

    Weather/Conditions – Temperature, humidity, altitude, and air density all impact engine performance.  Heat, high humidity, and thin air will all work towards reducing engine output

    Engine Health – Higher miles tends to result in increased build up and lower compression which can and will impact engine output.  Properly maintained engines will have better performance than abused or neglected engines.

    Supporting modifications – The highest power levels require supporting modifications.  Depending on the engine, this could mean forged internals, built transmission, upgraded fuel system, 110+ octane race fuel, etc.

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  • $2,499.00 $2,499.00

  • Prop 65 warning

    This product can expose you to chemicals including carbon black, silica - crystalline, formaldehyde, and lead which are known to the State of California to cause cancer, and lead, which is known to the State of California to cause birth defects or other reproductive harm. For more information go to

Weistec Horsepower 690
Weistec Torque 735
Manufacturer Weistec
Street legal in all the US States No
Stock Horsepower 591
Stock Torque 590
year make model trim engine
2019 Audi S8 Base (D4) Twin Turbo 4L V8 (EA825)
2018 Audi S8 Base (D4) Twin Turbo 4L V8 (EA825)
2017 Audi S8 Base (D4) Twin Turbo 4L V8 (EA825)
2016 Audi S8 Base (D4) Twin Turbo 4L V8 (EA825)
2015 Audi S8 Base (D4) Twin Turbo 4L V8 (EA825)
2014 Audi S8 Base (D4) Twin Turbo 4L V8 (EA825)
See more

Product Description

Weistec specializes in engineered performance solutions with designs that match and often exceed OEM levels of precision and quality. Our ECU Tune for the 4.0L TFSI EA825 V8 is designed to enhance the vehicle's characteristics without compromising the drivability or reliability of the vehicle. What does all this mean to you? More power, sharper throttle response, and a complete focus on the driver makes this the perfect addition to your Audi RSQ8 4M or Audi RS6 for a much more enjoyable experience. For more information please feel free to contact our performance specialists via phone or email at

ECU Tuning Process How do I get my ECU tuned?

Key Features

  • Increaded Boost

  • Optimized Fueling

  • Increased Torque Limits

  • Optimized Ignition Timing

  • Removed Speed Limiter