The M278 responds strongly to ECU tuning, with owners citing Renntech adding around 100 hp and 150+ lb-ft while feeling stock in normal driving, and a Revtech handheld tune claiming 500 hp / 650 lb-ft on California 91 octane. Multiple owners call the engine essentially bulletproof with these tunes.
ECU tuning: Renntech, Brabus and Revtech gains
Mercedes-Benz SL (R231) · driving