The turbo variant was upgraded with twin Garrett turbochargers and dual intercoolers. HS-110-2-SR diesel engine fitted with twin Holset turbochargers and intercooler. They are also used in internal combustion engines as superchargers and turbochargers. Roots superchargers impart significantly more heat to the air than turbochargers. In contrast to turbochargers, superchargers are mechanically driven by the engine. The engines utilize variable geometry turbochargers and Bosch piezo-electric injectors. This was necessary to make room for the twin turbochargers and intercoolers. Twin turbochargers are primarily used in Diesel engines. Turbo-back systems are generally produced as aftermarket performance systems for cars with turbochargers. AMG redesigned the exhaust gas turbochargers and added new engine electronics. This increases turbo lag significantly compared to unrestricted turbochargers. The N54 has two small low-pressure turbochargers to minimise turbo lag. Both engines were equipped with KKK turbochargers. Some variants additionally are equipped with Variable Nozzle Turbine (VNT) turbochargers. Twin KKK turbochargers, fitted with required air restrictors, allowed for .