High-performance TDO4 16T twin turbo upgrade for BMW 335i and 335xi N54 engines (2007–2010). Featuring 11-blade billet compressor wheels, 9-blade 713C turbine wheels, and a 10% larger A/R Hi-Si Mo casting, this kit delivers rapid spool and boosted airflow. Built and balanced in Michigan with upgraded internals and gaskets included—500 HP on high-octane pump gas, up to 650 HP with proper supporting mods.