Below you will find funnels that are used for damper housings. When fitting funnels, the flow into the motor is increased as the suction surface is increased with the funnel shape. You can get funnels in stainless, aluminum, and carbon material. There is also a difference in the length of the funnels. This is because the correct total length must be selected from the intake valve to the "start" of the hopper - there is a difference in the length in relation to how many revolutions the engine must run at. We get funnels from ex Jenvey.