GIAC Stage 1 Plus Audi A4 B5 ECU upgrade 1.8T Non-Drive by Wire


The Audi A4 B5 ECU upgrade adds horsepower, torque and better throttle response throughout the power band.

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We are pleased to present GIAC Stage 1 Plus Audi A4 B5 ECU upgrade (1997 - 2001) with 1.8 Turbo engine Non-Drive By Wire. The Audi A4 B5 ECU upgrade 1.8T replaces the standard software in your car's engine control unit without any physical modifications. In other words, the tune adjusts ignition timing, fuel delivery, boost settings, rev limiter and/or speed limiters to optimize performance and, in some applications, fuel economy. We can easily flash the ECU upgrade through the OBD-II port of your car. The initial installation is free of charge. For any subsequent changes, there will be an installation fee.

GIAC's understanding of vehicle controllers goes much deeper than simple table variable modification. While most "tuners" can only add and subtract from existing tables in the Engine Control Unit, we have the ability to change the functionality of the ECU at the code level, allowing for a complete calibration and even creation of new tables and functions.

GIAC map switching gives customers the ability to change performance settings in their vehicle without a visit to the shop. The switch takes a couple of seconds and can even be done while the vehicle is idling. We have tuning products for fuel quality ranging from 91 to 109 octane covering both normally aspirated and turbo models.

Please choose the local pickup option at check out, when you purchase the product.

Stage 1 Plus ECU upgrade

GIAC CO2 emissions

We designed the GIAC Stage 1 Plus ECU upgrade to dramatically increase torque and horsepower without sacrificing smooth drivability. In addition, the software accommodates numerous aftermarket performance modifications. Upgraded intake system, exhaust system and/or a charge cooler will further improve the performance.

The Audi A4 B5 ECU upgrade is available for the following ECUs (feel free to stop by our shop to check yours): 8D0907557N; 8D0907557P; 8D0907558M; 8D0907559; 8D0907559C.

Power gains from the Audi A4 B5 ECU upgrade 1.8T

Stock 91 octane by Audi 91 octane by GIAC Stage 1 Plus * 100 octane by GIAC Race mode **
Peak horsepower (hp) 148 200 210
Peak torque (lbf∙ft) 162 210 220
Max horsepower increase over stock +52 +62
Max torque increase over stock (lbf∙ft) +48 +58

* 91 octane fuel compatible. 93 octane fuel for optimum results.
** 100 octane fuel compatible. 105 octane fuel for optimum results. Optional switcher or remapping required.
- All fuel grades are North American AKI or (RON+MON)/2. For more details click here.
- Reported wheel figures measured on GIAC's in house 4WD Mustang Dynamometer. Also, HP and Torque figures are average engine estimates from wheel power and acceleration testing. To sum up, the results will vary depending upon environmental conditions, vehicle, transmission, vehicle health, operating conditions, temperatures, fuel grade, dyno type, dyno setup, and other modifications.

Hand-held flashloader switcher for the Audi A4 B5 ECU upgrade 1.8T

The optional GIAC’s Flashloader Handheld Switcher allows users to switch between optional maps/modes in the ECU upgrade with the touch of a button. To clarify, it is a pocket-sized, hand-held device that plugs directly into the OBD port. Furthermore, it uses serial flashing technology and requires no additional hardware within the ECU. To use the switcher, you should select the desired mode with the touch buttons. Cycling the ignition will save the new mode to the ECU’s memory and retain its state until switched again.

Hand-held flashloader switcher maps:

  • Stock mode - The ECU of the car is switched to factory settings.
  • Pump mode - The upgraded map which is optimized for pump fuel.
  • Race mode - It gives additional power and should only be used with high-octane fuel.
  • Valet mode - It will reduce the engine output to prevent other people (valets :)) from abusing your car.
  • Firewall mode - With this mode, you can password protect your handheld switcher so only you can switch maps.

The optional switcher with different modes for your Audi A4 B5 Stage 1 Plus starts at $200 (contact us for details).

Requirements and recommendations

GIAC checklistRequirements

There are no additional parts that are required to be installed for the Stage 1 ECU tune.

GIAC recommendationsRecommendations

Adding a quality performance intercooler, intake and/or cat back exhaust system will improve performance.
Also, we highly recommend the car to be in perfect mechanical condition.

Installation details

After you purchase the software, we will contact you to schedule an appointment to install it. The installation must be done at our shop in Culver City, CA (full address) with a physically present car.

Give us a call at (562) 448-2599, send us an email to, or also use our contact form (click here) if you have any questions.

Warranty and returns

GIAC warrantyWarranty

GIAC products carry a 30-day money-back guarantee. Also, GIAC Flashloader Handheld (FHH) and Flashloader Mobile (FLM) devices carry a 30-day money-back guarantee and a one-year GIAC product replacement guarantee. For details click here.

GIAC returnReturns

If you are not satisfied with the product, you can return it within 30 days for a full refund of the software (less installation). To clarify, all returns must be made at the original point of sale within 30 days of receipt of merchandise. Custom designed or engineered products are non-returnable.

About GIAC

GIACGIAC is a software engineering company with many years of experience tuning cars (since 1997). Our software replaces the standard software in your car's engine control unit and/or transmission control unit. We are designing after-market software for Porsche ®, Audi ®, VW ®, and Bentley ®. In addition, we have a long history of tuning many other European makes on a case-by-case basis. Also, our accessory products include the Flashloader handheld switcher, which enables easy switching between multiple GIAC maps and the stock map.
GIAC has produced the highest quality performance software for Audi ® vehicles for longer than most other tuners have been in existence. In fact, all GIAC calibrations for VAG cars, whether for a sedan / sportback, SUV / Wagon, or Audi Sport ® vehicles, reflect the knowledge and rigorous test methodology we have developed since 1997. Even more, GIAC designs and develops, in house, software and hardware tools for reading and writing vehicle controllers, for creating and compiling vehicle calibrations, and for vehicle parameter logging. We succeed with these cars year after year because we have skills, knowledge, and resources to get it right.
Pictures used for marketing purposes only, actual product may vary.


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