Stage 2 Billet Turbo Upgrade for Mercedes-AMG GT / GT S / GT C / GT R (R190) – M178 4.0L BiTurbo

The Stage 2 Billet Turbo Upgrade is the largest factory-housing turbo upgrade available for the M178 4.0L V8 BiTurbo — engineered for serious power while keeping true bolt-on fitment in the AMG GT. Built for high-boost street cars, track builds and setups planning for more power later, the Stage 2 turbo dramatically increases airflow through custom billet internals while retaining OEM-style installation.

Vehicle Fitment

• Mercedes-AMG GT (R190) — M178 4.0L V8 BiTurbo
• Mercedes-AMG GT S (R190) — M178 4.0L V8 BiTurbo
• Mercedes-AMG GT C (R190) — M178 4.0L V8 BiTurbo
• Mercedes-AMG GT R (R190) — M178 4.0L V8 BiTurbo

What Makes the Stage 2 Turbo Different

Built around the largest turbo configuration that still fits inside the factory housing footprint — massive airflow capability without the complexity or fitment problems of a full custom turbo system.

• Largest factory-housing turbo available for the platform
• Billet compressor wheel — 55mm inducer / 73mm exducer
• High-flow turbine wheel — 55mm
• Fully bolt-on installation

Factory turbo, for reference: compressor 41.7mm inducer / 56mm exducer · turbine 44.5mm / 50mm · A/R 0.57. The size difference shows how much additional airflow capacity this upgrade provides over stock.

What These Turbos Need

The turbo will physically install on a stock car. It will not make its numbers on one.

Core Return & Wastegate Instructions

• Core return required
• Remove your factory wastegate actuators before shipping your cores
• If turbos are received with wastegates installed, do not use them — reuse your original factory wastegates for known calibration and reliability

Who This Turbo Is For

• Owners targeting 850–1000+ HP
• Track-focused or high-boost street builds
• Future-proof setups planning for more power later

Need help confirming fitment or supporting mods? Contact us before ordering and we will help you build the setup correctly the first time.