Yours is only a knock indicator, not part of a control system, correct? I hear you on the OEM effort to dial in/tune for best results. Kinda of my thinking here, might as well place it well. I'm thinking, away from cam/valve linkage, not in the head, but close to the head gasket. Using the drain position, I wonder if the surrounding water/jacket might dampen some of the shock waves we are trying to "hear". Using two was because its a long head/block, and MS3 has that provision. On a Slant that makes the sensor(s) very close to the exhaust heat, one of my concerns, as i have zero idea how this effects a piezo? sensor circuit. Probably just chasing my tail, again.
