AMG GT S Stage 3 Turbo Upgrade: 776 WHP on Low Boost with Methanol

776 WHP on Low Boost — And We're Not Done Yet

The Mercedes-AMG GT S is already one of the most capable platforms in the AMG lineup. The hand-built M178 4.0L twin-turbo V8 delivers 515 hp from the factory — but with YPG Motorsport's Stage 3 turbo upgrade package, we've just pulled 776.51 WHP on low boost with methanol injection on a Dynojet chassis dynamometer.

That's not full power. That's the conservative map. The turbos have significantly more headroom, and full boost numbers are targeting well north of 900 WHP.

What Does Stage 3 Mean for the AMG GT S?

A Stage 3 build on the M178 platform goes beyond bolt-on modifications. While Stage 1 and Stage 2 tunes work within the limits of the factory turbochargers, Stage 3 replaces them entirely with upgraded units capable of much higher airflow and boost pressure.

The YPG Motorsport AMG GT S Stage 3 package includes:

  • Upgraded twin turbochargers sized for 900+ WHP capability
  • YPG Motorsport custom ECU calibration (Stage 3 map)
  • Methanol injection system for charge cooling and effective octane boost
  • Supporting fuel system upgrades
  • Downpipes and full exhaust for optimal flow

Every component is matched to work as a system. The ECU calibration is developed in-house by YPG Motorsport and tuned specifically for this turbo and fueling combination.

Dyno Results: 776 WHP on Low Boost

The car was strapped to a Dynojet chassis dynamometer and pulled 776.51 WHP at 236.43 km/h on the low boost map with methanol injection active. The dyno correction factor was STD with Smoothing 5.

Key observations from the dyno curve:

  • Flat, sustained power delivery — the curve holds above 500 WHP from the midrange all the way through the top end, with no dips or surges
  • Clean calibration — no signs of knock pull, fuel trim issues, or boost instability
  • Significant headroom remaining — this is the low boost map, meaning full boost targets are substantially higher

For context, a stock AMG GT S puts down approximately 450–460 WHP on a Dynojet. A fully built Stage 2 setup on stock turbos typically peaks at 600–680 WHP. This Stage 3 result on low boost is already exceeding most shops' full-power Stage 3 numbers on competing platforms.

Why Methanol Injection Matters

Methanol injection serves two critical purposes in a high-boost forced induction setup. First, it dramatically lowers intake air temperatures — cooler air is denser, which means more oxygen per combustion cycle and more power. Second, methanol effectively raises the octane rating of the fuel charge, allowing the ECU to run more aggressive ignition timing without detonation risk.

On the AMG GT S Stage 3, methanol injection is a key enabler for making reliable, repeatable power at elevated boost levels. It's not optional at this power level — it's part of the engineering.

How Does This Compare to Other AMG GT S Builds?

The M178 AMG GT / GT S / GT C aftermarket is competitive. Here's where YPG Motorsport's Stage 3 result sits relative to the broader market:

  • Stock AMG GT S: 450–460 WHP (Dynojet)
  • Stage 1 ECU tune: 530–560 WHP
  • Stage 2 (stock turbos, full boltons): 600–680 WHP
  • Stage 3 (upgraded turbos, most shops, full boost): 800–950 WHP
  • YPG Motorsport Stage 3 (low boost, methanol): 776 WHP — and climbing

We're making more power on the conservative tune than many competitors deliver on their full-power calibrations. When the high boost map is finalized, this platform is targeting four-figure territory.

M178 Platform Expertise

The M178 engine shares its architecture with the M177 found in the C63, E63, GLC63, and GT 63 — but with key differences in turbo sizing, cooling, and engine management. YPG Motorsport has extensive experience across the entire M177/M178 family, including holding the world record for the fastest Mercedes-AMG C63 W205 quarter mile at 9.97 seconds and 828 WHP, set at Beech Bend Raceway Park, Kentucky on April 9, 2019.

That same calibration expertise and turbo system engineering is applied to every M178 GT S build. Whether you're in Kuwait, the GCC, or anywhere worldwide via our YPG Flash remote tuning service, the same proven performance is available.

Available Worldwide

YPG Motorsport offers Stage 1, Stage 2, and Stage 3 turbo upgrade packages for the Mercedes-AMG GT S and the full M178 platform lineup. ECU tuning is available via:

  • YPG Flash: Remote OBD tuning via AutoTuner — tune from anywhere in the world
  • YPG Bench: Mail-in bench ECU service for markets where OBD access is restricted
  • In-house: Full installation and calibration at our Kuwait facility

Contact us at sales@ypgmotorsport.com or browse our AMG GT S performance catalog to get started.

Related M177 / M178 Stage 3 Builds

The AMG GT S is the latest M177/M178 platform to receive the YPG Stage 3 treatment. See our other Stage 3 turbo build guides for the same engine family:

AMG GT S Performance Products

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