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BMW M3 & M4 Downpipe Guide — G80 G82 S58 Catted vs Catless, Gains & Tuning
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...