15" high. Under the bridge deck I put in an eye bolt. I hung a piece of 1/8" stainless rod from that eye that loops under the injection elbow. The eye bolt is located so that the riser hangs from the bridge deck in the proper spot to attach to the manifold. My riser is mounted to the manifold with two flanges held together by a clamp. Basically almost none of the weight of the riser is supported by the manifold. It probably transmits some sound into the bridge deck, but not much.