Just so everyone is clear about how the shim will LOWER the lid, check out the attached sketch...
Just as if you ROTATE
the hood hinge on one of these cars to raise and lower the hood it will raise or lower it WAY
more than simply raising the hinge up or down on the fender. Shimming the trunk hinge will effectively "rotate" the angle notation to the axis of the hinge and raise or LOWER the lid.
At least that is how I understand what is happening.