The Turbosmart Kompact valves are designed as direct replacements for the factory BMW bypass valves and offer quicker action, better flow and higher strength under boost. The Kompact series is also substantially smaller than other valves on the market, making installation a breeze in tighter engine bays such as that of your 135 or 335. The Kompact Plumb Back system recirculates all excess pressure back into the intake system. Great for those enthusiasts trying to stay stealthy but still want the performance and reliability benefits of a quality valve. This kit comes with two BOVs, durable silicone boost hoses, and all necessary installation components.