The Mercedes CLS 450 (3.0T) 367hp (C257 - 2021 ->) produces 367bhp and 500Nm in standard form. Our Stage 1 ECU tuning file raises output to 420bhp and 620Nm, a gain of 53bhp and 120Nm, with no hardware modifications required. The file is delivered through the ByteFLASH portal and is ready to write to the vehicle.