How to Upgrade the Performance of an Audi RS4

Written by jeff slater
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How to Upgrade the Performance of an Audi RS4
Simple engine modifications can unleash vast amounts of horsepower. (old engine image by John Sfondilias from

Designed to compete with BMW's powerful M3, the German engineered Audi RS4 is a high performance, limited production all-wheel drive sports car, available in either wagon or sedan body styles. Building upon Audi's popular A4, the RS4 receives a thorough makeover in order to transform it into a true exotic grand touring machine. More aggressive bodywork is added front and rear, with bulging fenders, (in order to accommodate low profile near-race-spec tires) and redesigned diffuser in the back which provides additional downforce by smoothing out airflow and minimising lift. Originally offered in twin turbo, and then with a normally aspirated V8, the RS4 is a fast car from the factory, however there is still untapped power lurking under the hood.

Skill level:

Things you need

  • Tune-up kit
  • Air Intake
  • Exhaust system
  • ECU upgrade
  • Dyno Tuning

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  1. 1

    Perform a full vehicle tune-up (including changing all critical fluids, such as oil, coolant, transmission fluid and replacing the spark plugs/ wires). Before modifying the RS4 for additional power, make sure it is in peak running condition; tuning the engine to increase output will undoubtedly place more stress on several components, causing faulty or worn out parts to fail.

  2. 2

    Install a high-flow intake. This can range from a sinple drop-in air filter upgrade, to an entire cold air system, which replaces the factory induction piping. This allows the engine to breathe better for faster turbo spool up, and more power and torque at high engine speeds.

  3. 3

    Add an aftermarket exhaust. The factory exhaust system, although quite capable, is designed to meet stringent noise and emissions levels, installing larger diameter exhaust piping will reduce back pressure and liberate more ponies throughout the RPM band.

  4. 4

    Install a custom ECU. Now that the critical intake and exhaust systems are upgraded, its time to maximise performance. The ECU can be reprogrammed or replaced to provide custom fuel and timing maps. This not only dramatically increases horsepower, but also ensure a smooth running vehicle with proper idle and engine speed limits.

  5. 5

    Tune your RS4 on a 4 wheel drive Dyno. In addition to measuring vehicle horsepower over the entire power-band, it provides a safe environment to adjust various settings such as fuel pressure, boost levels and will further tweak power delivery on both pump gas and racing fuel (if desired).

Tips and warnings

  • Always monitor coolant temperatures closely while placing heavy loads on the engine.
  • Never exceed the recommended maximum engine speed.
  • Installing some form of knock detection alert system is suggested to avoid possible pre-ignition, which can result in engine damage.

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