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M177 HPFP Upgrade Guide: 250bar vs 350bar — Which High Pressure Fuel Pump Kit Do You Need?
The stock high-pressure fuel pump on the Mercedes-AMG M177 4.0L V8 BiTurbo is the first component to hit its limit when you push beyond factory power. Whether you're running a Stage 2 ECU calibration, upgraded turbos, or ethanol-blended fuels, the OEM HPFP cannot deliver enough volume to maintain stable rail pressure — and that means lost power, misfires, or worse. This guide covers everything you need to know about upgrading the HPFP on the M177 platform: what the stock system's limits are, how 250bar and 350bar kits compare, which models fit, and what supporting modifications you need. Why the Stock...