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Audi RS6 Avant C8Stage 1 to Stage 4 tuning guide

The C8 RS6 has a 4.0 twin-turbo V8 with the turbos inside the V, and it responds strongly to software: tuners claim roughly 80 to 160 hp from a flash on pump fuel. The limits are heat, the gearbox software's torque limit at big power and, on European cars, the petrol particulate filter.

Years
2020–
Engine
4.0 TFSI twin-turbo V8 (EA825)
Gearbox
8-speed ZF automatic (Tiptronic)
Stock power (US)
591 hp / 590 lb-ft
Red Audi RS6 Avant C8 parked at a mountain viewpoint

Power by stage

Stage 1 and 2 are the tuners' own published figures for the standard 591 hp car on pump fuel (91–93 US / 95–98 RON). Stage 3 and 4 are tuners' package claims, often on higher-octane fuel. Real results depend on fuel, weather and the individual car.

Stock591 hp
Stage 1668–753 hp Stage 2720–819 hp Stage 3760–950+ hp Stage 41,000+ hp

Names with an arrow go straight to that part's product page for this car. Names in a dashed outline are other brands that make the part; exact links for them are being added.

1

Software only

+77 to +162 hp

A new file for the engine computer, with no hardware needed. APR and 034Motorsport say their Stage 1 delivers full torque without a separate gearbox (TCU) tune. The 2024-on RS6 performance starts at 621 hp; APR claims 745 hp for it on 93 octane. Higher figures in the table, on 100 or 104 octane and ethanol blends, need race fuel you can't buy at a normal pump.

Typical cost: software $950–$2,599 (034, IE, APR, MTM), or $1,500 for 034's engine and gearbox bundle; Litchfield £1,800 including VAT. Unitronic sells through dealers only.List prices, Sept 2026, before shipping, import tax and fitting.

Stage 1 tunes compared

TuneFuelClaimed powerClaimed torqueNotes
APR ECU Upgrade91–104 US685–767 hp731–804 lb-ftRange across fuels; APR says no gearbox tune is needed for full torque
Unitronic Stage 191 US / 95 RON700 hp694 lb-ft
Unitronic Stage 1+93 US / 98 RON753 hp709 lb-ft728 hp with the stock intake
034Motorsport Dynamic+ ECU and TCU93 US743 hp730 lb-ftIncludes a gearbox file; 730 hp on 91 US; 2022-on cars need an unlock harness
IE Stage 193 US / 98 RON690 hp780 lb-ft668 hp on 91 US / 95 RON
MTM Performance Upgrade—722 hp700 lb-ftMTM calls its figures approximate
ABT Power—700 PS880 NmWith a German TÜV report and ABT's warranty
Litchfield Stage 1—700 PS—UK tuner

Recommended with Stage 1

  • Gearbox (TCU) tune optional 034MotorsportUnitronic

    APR and 034 say Stage 1 needs no separate gearbox tune; 034 sells its engine file bundled with one.

  • Intake optional Eventuri intake (C8 RS6/RS7)UnitronicIE

    Eventuri claims 45–50 hp more with its intake on a Stage 1 car.

Before you buyCars from about 2022 on usually need a bench or bootloader unlock before any tuner can flash the engine computer; ask the shop how they do it. In Israel you can only buy 95 and 98 octane at the pump, so look at the 91–93 US figures.
2

Intake, intercoolers and downpipes

+129 to +228 hp

Stage 2 adds the parts that let the turbos breathe: intakes with turbo inlets, bigger intercoolers and downpipes, with a file written for them. Unitronic claims 819 hp on 98 RON with its full package. On European cars the petrol particulate filter (GPF) matters: some tuners, such as Litchfield, build Stage 2 around exhausts that keep it.

Typical cost: software $1,195 (CarBahn) or $3,049 (MTM); Litchfield with an exhaust £5,905–£9,782 before VAT.List prices, Sept 2026, before shipping, import tax and fitting.

Stage 2 packages compared

PackageFuelClaimed powerClaimed torqueRequired hardware
Unitronic Stage 293 US / 98 RON819 hp760 lb-ftUnitronic intake and turbo inlets, CSF intercoolers and Unitronic downpipes
MTM Stage 2—775 hp780 lb-ftAn intake with turbo inlets
CarBahn EVO Stage 293 US757 hp (calculated)808 lb-ft621 hp measured at the wheels; needs a bench unlock
Litchfield Stage 2—730 PS—GPF-back exhaust (Milltek or Akrapovič) and a K&N filter; keeps the GPF

Parts list

  • Intake with turbo inlets required Eventuri intake (C8 RS6/RS7)UnitronicIE

    Eventuri claims 60–80 hp more with its intake on a Stage 2 car.

  • Intercooler upgrade required CSFWagner Tuning

    The turbos sit inside the V, so heat builds quickly. Bigger intercoolers keep the power up on repeated pulls.

  • Downpipes most packages Unitronic downpipes (catalysed)

    Required for Unitronic's Stage 2. Litchfield's Stage 2 uses a GPF-back exhaust instead.

  • GPF-back exhaust optional Milltek SportAkrapovič

    Keeps the particulate filter. Mostly sound, and part of Litchfield's Stage 2.

Before you buyRemoving or replacing the particulate filter on a European car breaks emissions rules and fails inspection, and even catalysed downpipes usually need approval to be road legal. Keep the original parts.
3

Upgraded turbos

760–950+ hp

Stage 3 replaces the turbos, and from here the gearbox software matters: Unitronic says the factory gearbox computer limits torque, and its Stage 3 gearbox file raises the limit to 1,300 Nm. Boost also goes past what the factory 3-bar pressure sensors can read, so 4-bar sensors are part of the package.

Typical cost: IE software for Pure900 turbos $2,299; the turbos are extra.List prices, Sept 2026, before shipping, import tax and fitting.

Stage 3 packages compared

PackageFuelClaimed powerClaimed torqueNotes
Unitronic Stage 3 with TTE1020 turbos93 US / 98 RON936 hp830 lb-ftNeeds the Stage 3 gearbox file, 4-bar sensors, intake, intercoolers and downpipes
IE with Pure900 turbos93 US / 98 RON800 hp824 lb-ft903 hp on 104 octane
Wheelsandmore Stage IV—965 PS1,250 NmUpgraded turbos
ABT Power R—760 hp920–980 NmABT turbos and intercoolers, on the 630 PS performance

Parts list

  • Upgraded or hybrid turbos required TTE1020 turbos (via Unitronic)Pure TurbosABT

    Sold as matched pairs with a file written for them.

  • Gearbox (TCU) tune with a higher torque limit required Unitronic034Motorsport

    Unitronic's Stage 3 gearbox file raises the torque limit to 1,300 Nm.

  • 4-bar boost pressure sensors required UnitronicIE

    Boost goes beyond what the factory 3-bar sensors can read.

  • Intake, intercoolers and downpipes required From Stage 2

    The Stage 2 hardware stays on the car.

Before you buyBudget for the full package: turbos, gearbox software, sensors, fuel and labour. The biggest figures need 104-octane race fuel or ethanol blends.
4

Maximum builds

1,000+ hp

The top packages from European tuners reach about 1,000 hp: MTM claims 1,001 hp for its Stage 4, and Wheelsandmore 1,010 PS for its Stage V, which replaces the catalysts and particulate filters and so isn't road legal. We found no documented forged-engine C8 builds, so treat these as the practical ceiling. These are tuners' top packages, not everyday builds.

Parts list

  • Tuner's complete top package required MTM Stage 4 (1,001 hp)WheelsandmoreBTM

    Upgraded turbos, a larger intake and matching engine and gearbox software, sold as one package.

  • Custom tune and gearbox software required MTMUnitronic

    At this power every car is tuned on its own.

  • Cooling, brakes and tyres required CSFWagner Tuning

    The car weighs more than two tonnes; cooling, brakes and tyres all have to keep up with the engine.

Before you buyStage 4 is a full engine and driveline project, not a bolt-on. Choose one shop to build, tune and stand behind the whole package, and check which parts are road legal where you live.

Questions to ask the shop

  1. Does this power level need a gearbox (TCU) tune on my car, and is the file included?
  2. My car is a 2022 or later model: do you need a bench or bootloader unlock, and can the dealer see it?
  3. On a European car, does your Stage 2 keep the particulate filter, and are the parts approved for road use?
  4. Which fuel is this file written for (95 or 98 RON, or an ethanol blend), and what happens if I fill up with lower octane?
  5. Is your figure from your own dyno on my version (600 PS or the 630 PS performance), and is it at the crank or the wheels?
  6. How do you log intake temperatures and knock, and do you recommend intercoolers at this stage?