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The Mercedes-AMG GT family runs the M178 — the dry-sump variant of AMG's 4.0L twin-turbo V8. Like its wet-sump sibling (the M177), the M178's stock high-pressure fuel pump is the first bottleneck when pushing beyond factory output. This guide covers HPFP upgrade options specifically for the AMG GT, GTS, GTC, GTR, and Black Series. M178 vs M177 — What's Different? The M178 shares the same 4.0L twin-turbo V8 block architecture as the M177 but uses a dry-sump lubrication system instead of wet sump. This allows the engine to sit lower in the chassis for a lower center of gravity —...

The AMG GT platform — GT, GTS, GTC, GTR, and GTR Pro — uses the M178 4.0-liter twin-turbo V8, a dry-sump variant of the M177 with dedicated turbo hardware and a unique exhaust layout. The factory catalytic converters sit directly downstream of the turbochargers in one of the tightest engine bays in the AMG lineup, creating significant backpressure that limits turbo efficiency and total power output. Replacing them with race downpipes is the single most effective bolt-on modification for any AMG GT variant. This guide covers catless versus 200-cell high-flow cats, real-world power gains by variant, exhaust sound characteristics, fitment...