Black Silicone Hose by Mishimoto. Interior Material: Heat-Resistant Embedded Fibers. Exterior Material: Silicone. Inner Diameter: 1.33in. Outer Diameter: 1.73in. The Mishimoto Silicone Throttle Body Hose is a direct OEM replacement for the stock rubber hose. The stock rubber throttle body hose, which connects the cold pipes from the turbo up to the throttle body, can wear out from oil, engine heat, and the stock clamp design. These factors, when coupled with the constant movement of the cold pipes, put too much stress on the rubber construction. Deterioration of the rubber can lead to a �boost leak,� letting air escape from the connector between the turbo and the engine, robbing the engine of horsepower and reducing overall performance.