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BMW M340i / M440i B58 ECU Tuning Guide The BMW B58 3.0-litre twin-scroll turbocharged inline-six is one of the most tuneable engines BMW has ever produced. Found in the G20 M340i, G22 M440i, and their xDrive variants, this engine delivers 382 HP and 369 lb-ft of torque in stock form — but its true potential is far greater. With a well-calibrated ECU remap, the B58 can reliably produce north of 450 HP on completely stock hardware, making it one of the best platforms for performance tuning in the current BMW lineup. In this comprehensive guide, we break down every tuning...