We put these in the front Koni Sport
KONI do not make a strut for the Z3 M Coupe so we had to ct the strut to fit the insert.
Here is how it is done
Place strut in a vice and mark the center.
The inner diameter is 26mm so 13mm is center.
Mark it with a punch and start with a small bit (5mm) and drill progressively with bigger bits to 12,5mm or 13mm if you do not have an in between drill.
Drain the oil.
This is what the front of the strut looks like with it rubber cover
Remove the front rubber cover and mark the cutting line with tape making sure that it is placed equidistant from the crimps on the strut
Put goggles on and cut along the tape mark with a grinder.
Roughly a 4mm deep cut will suffice.
Remove the shock innards and you are ready to install the insert.
Secure with the provided cap screw.
Cap screw is torqued to 75Nm.
Replace rubber boot on top of strut and you are done.