Vel, etter litt sprikende meninger sendte jeg en mail til G3 og her er svaret: The shim extender mounting holes are 1 cm forward of the traditional Targa holes. Thus if you do use the shim extender holes to mount your Targa shim, you will have moved the 3pin line 1 cm forward (in front of the balance point, if I understand you correctly). Your other option is to plug the shim extender holes, and to then re-drill your holes one cm back. This would give you the same mounting position which you currently have.
Kanskje dette kan være til hjelp for andre også en gang...