G-Power’s GP-820 package is listed at 820 hp (603 kW) and 1,000 Nm for the F9X M5, M8, X5 M and X6 M family. It is a hardware-supported tuning package—not a software flash by itself—and the available sources do not establish that an 820-hp modified M8 has been independently tested on track.
What the GP-820 claims—and which M8 it refers to
G-Power USA lists the GP-820 Stage 3 output as 820 hp (603 kW) and 1,000 Nm. Those are the tuner’s figures for its F9X M5/M8/X5M/X6M application, not independent test results or a universal specification for every M8 year, market or configuration. G-Power USA’s current GP-820 listing is the primary source for the package claim.
For context, BMW’s 2019 U.S. specifications for the 2020 M8 Gran Coupe listed 600 hp and 553 lb-ft for the standard model, and 617 hp and 553 lb-ft for the Competition. These are the manufacturer’s original figures for those U.S.-market Gran Coupe versions; they should not be treated as specifications for every later M8 or another region. BMW’s 2019 M8 Gran Coupe release provides the model-specific baseline.
GP-820 is a hardware package, not just an ECU tune
G-Power’s product page says GP-820 requires its DeepTone exhaust system, Motorsports exhaust and turbochargers. It also says ECU tuning is performed by G-Power dealers, and ECU units produced after June 2020 need unlocking for an extra charge. Confirm the individual car’s ECU and required parts with the tuner before treating the listed configuration as a fitment guarantee.
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How the listed stages differ
| G-Power stage | Claimed output | Hardware requirement stated by G-Power | Listed fuel compatibility |
|---|---|---|---|
| GP-700 | 700 hp / 850 Nm | No additional hardware requirement stated on the product page | 91 and 93 octane |
| GP-740 | 740 hp / 900 Nm | DeepTone exhaust | 91 and 93 octane |
| GP-780 | 780 hp / 950 Nm | DeepTone and Motorsports exhaust | 91 and 93 octane |
| GP-820 | 820 hp / 1,000 Nm | DeepTone and Motorsports exhaust, plus G-Power turbochargers | 91 and 93 octane |
Outputs, parts and fuel compatibility in this table are claims from G-Power USA’s stage listing. Its page does not establish local emissions legality, warranty coverage or suitability for a particular car’s condition. Those questions need to be checked for the car’s jurisdiction and configuration.
What “track-day aspirations” does—and does not—mean
BMW described the factory M8 as having engineering intended to cope with track-driving demands. Its 2019 U.S. releases describe separate water circuits, additional engine and transmission oil cooling, and a map-controlled oil-suction pump with a secondary front oil-pan chamber. BMW linked those provisions to greater thermal demands and extreme lateral and longitudinal forces during track driving. See the M8 Gran Coupe release and M8 Coupe and Convertible release.
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- More Power: Max gains of 22 WHP and 18 lb-ft of torque @ 6500 RPM on an otherwise stock vehicle
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That is evidence about the factory car’s design intent, not proof that the G-Power-modified car can sustain 820 hp through track sessions. The cited sources do not provide an independent GP-820 track test, lap time, brake-temperature data or durability result. Extra power alone cannot establish track readiness; the available information does not quantify how the modified setup performs under repeated track use.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Why other 820-output reports may describe a different setup
Reports using the same headline output do not necessarily describe the same package or units. Auto Motor und Sport’s 2020 report on an M8 Competition Cabriolet gives 820 PS and 1,000 Nm and describes turbochargers, downpipes and exhaust for that configuration. G-Power USA’s current U.S. page instead states 820 hp and names its own required hardware. Do not combine those parts lists as though they are one verified build. Auto Motor und Sport’s report and G-Power’s U.S. listing have different contexts.
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A 2025 PistonHeads report also describes a G-Power G8M Bi-Turbo at 820 hp and 738 lb-ft. That is a separate report and its figures should not be silently substituted for the GP-820 page’s 1,000 Nm claim. PistonHeads’ G8M Bi-Turbo coverage supplies that reported output.
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What to verify before choosing the package
- Exact application: Confirm that the car’s model, year and configuration are covered by the package rather than assuming all M8 variants share fitment.
- Parts and ECU: Ask the dealer to confirm the full hardware list, ECU version and whether an unlock is needed.
- Fuel and local rules: The page lists 91- and 93-octane compatibility; confirm what that means for the fuel available where the car will run, and check emissions requirements locally.
- Warranty and track use: Confirm warranty implications and ask what evidence or support applies to sustained track driving. The listed output is not a track durability guarantee.
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
