Ducati Diavel Workshop Manual page 583

Exhaust system
If removed, tighten the horizontal lambda sensor (20) to a torque of 25 Nm ± 10% (Sect. 3 - 3, Frame torque settings).
Check the presence of clips (15) on the upper exhaust pipe (19).
Fit the aramid washers (12) on the screws (11) using the recommended threadlocker.
Insert the screws (11) in the holes of the heat guard (13).
Insert the other two washers (12) and the spacers with collar (14) on the protruding ends of the screws (1).
Note
The two spacers (14) must be oriented with the collar (W) facing the heat guard (13) as shown.
Fit the heat guard (13) starting the screws (11) and tighten the screws (11) to the torque of 8 Nm ± 10% (Sect. 3 - 3,
Frame torque settings), making sure the washers (12) are centred to the collars (W) of the spacers (14).