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The McLaren 720S is powered by the M840T — a 4.0-litre twin-turbo flat-plane-crank V8 that produces 710 HP from the factory. It is one of the most technologically advanced engines in any production car, and it has significant untapped performance potential. The factory catalytic converters, positioned downstream of each turbocharger, are the single biggest restriction in the exhaust system. Replacing them with performance downpipes is the foundation of serious 720S power builds. The M840T Exhaust Architecture McLaren’s M840T is a bespoke unit — not shared with any other manufacturer. The flat-plane crankshaft delivers an even firing order that naturally produces...

The Mercedes-AMG G63 W463A houses the same M177 4.0-litre twin-turbo V8 found in the C63 — but in a body-on-frame SUV that weighs over 2,500 kg. With 577 HP from the factory, the G63 is absurdly fast for its size. But the factory exhaust system, constrained by emissions compliance and the G-Class’s unique exhaust routing to the distinctive side-exit pipes, leaves meaningful power on the table. Upgrading the downpipes is the single most effective bolt-on modification for unleashing the M177’s full capability in the G-Wagen chassis. The G63 Exhaust Challenge The G63’s exhaust system is unique. The hot-vee M177 engine...

The BMW F90 M5 uses the S63B44T4 — a 4.4-litre twin-turbo V8 that produces 591–617 HP from the factory depending on variant. It is one of the most potent sedans ever built, and it has substantial untapped potential locked behind factory exhaust restrictions. The stock catalytic converters downstream of each turbocharger are the primary bottleneck, and replacing them with performance downpipes is the foundation of any serious M5 build. Why the S63 Needs Downpipes The S63 positions its two twin-scroll turbochargers outboard of the cylinder banks in a traditional hot-outside-vee layout. Each turbo feeds exhaust through its own catalytic converter...

The BMW G80 M3 and G82 M4 are powered by the S58 3.0-litre twin-turbo inline-six — BMW M Division’s most potent six-cylinder production engine. With two mono-scroll turbochargers, a closed-deck block, and forged internals from the factory, the S58 is engineered to handle serious power. But the stock exhaust system, specifically the catalytic converter section immediately downstream of the turbos, is the single biggest restriction holding it back. This guide covers everything about upgrading the downpipe on the G80/G82 platform. The S58 Exhaust Layout Unlike V8 twin-turbo engines with individual downpipes per bank, the S58 inline-six uses two turbochargers feeding...

The Mercedes-AMG GT is a front-mid-engine grand tourer built around the M178 4.0-litre twin-turbo V8 — a hand-assembled unit that shares its displacement and hot-vee architecture with the C63’s M177 but differs significantly in its dry-sump lubrication, engine mounts, exhaust routing, and ECU calibration. The AMG GT’s factory exhaust system is designed with emissions compliance and NVH refinement as priorities, and the catalytic converters sitting directly downstream of each turbocharger are the primary flow restriction in the system. The Factory Exhaust Restriction In the AMG GT, both turbochargers sit inside the cylinder bank vee, feeding exhaust through tightly packaged catalytic...