[sjf911]

After looking over the case extensively, I came to the conclusion that it was also the safest place to locate the sensor. I don't know what effect the gasket would have other than damping "ring". The bolts that clamp the cover should be more than capable of transmitting the acoustic signal. The Knocksense control unit does have a potentiometer for adjusting sensitivity and is supposedly tuned to the detonation frequency distribution.
Obviously mounting the sensor on the case prohibits identification of individual cylinder detonation which is the advantage of mounting dual units on bridges over the cylinders. MS-II on the other hand has no provisions for individual cylinder knock identification and ignition control.