The Mercedes CLS 350 (2.0T) 299hp (C257 - 2018 - 2020) produces 299bhp and 400Nm in standard form. Our Stage 1 ECU tuning file raises output to 350bhp and 470Nm, a gain of 51bhp and 70Nm, with no hardware modifications required. The file is delivered through the ByteFLASH portal and is ready to write to the vehicle.