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The M157 5.5-liter twin-turbo V8 is one of Mercedes-AMG's most iconic powertrains — a hand-built engine that powered the previous-generation E63, ML63, and G63 from 2012 through 2018. With factory outputs ranging from 550 HP to 585 HP, the M157 was already formidable from the factory. But the factory catalytic converters create a massive restriction downstream of the turbochargers that limits both power delivery and turbo efficiency.This guide covers everything you need to know about upgrading downpipes on your M157-powered Mercedes: catless versus high-flow catted options, real-world power gains, exhaust sound changes, fitment across all M157 models, and why an...

Why Upgrade Downpipes on the AMG G63?The Mercedes-AMG G63 W463 uses the M177 4.0L twin-turbo V8 — the same engine found in the C63 S, E63 S, GT63 S, and GT R. The factory downpipes include two primary catalytic converters that restrict exhaust gas flow from the turbos. Upgrading to high-flow downpipes is the most impactful bolt-on for reducing turbo lag, boosting peak power, and giving the G-Class a deeper, more commanding exhaust note.Catless vs 200-Cell — Comparison Table Type HP Gain (with Stage 2) Torque Gain Emissions Sound Best For Catless (race) +80–120 WHP +90–130 lb-ft Off-road only Very...