FTP E8X E9X N55 charge pipe for 135i 335iIncreased FlowDirect OEM Replacement3in Mandrel Bent Aluminum Construction4 Play Silicon Couplers The FTP BMW N55 Charge Pipe both increases flow and improves the reliability of your twin turbo BMW. The 3" mandrel bent aluminum pipe replaces the brittle factory plastic pipe which can fail under increased boost pressure. The increased piping size helps to reduce turbulence and maximize flow into the engine.