Knock chip has adjustable gain. In 1.1.90 you can adjust gain for each cylinder individually.
As I knew for BOSCH non-resonant sensors with hole for screw gain = 2 is not too much. Because output voltage is really low.
You also can rise signal level by decreasing integral constant. But first try to find gain for each cylinder - you want equal signal levels when WOT. Then adjust integral constant so that maximum levels is 200-300 when no knock.
Please use 100% Knock reference for all cylinders
Gints