Did you make something to act as a hot air dam or buy a replacement piece? I just fixed my resistor pack problem and was going to do the insulating thing as well but that part is also missing on my car.
According to the Manuals, the parts are:
Gutter Extension Panel, RHD A117B0703K 1
Gutter Extension Panel, LHD A117B0704K 1
The hot air dam is an integral part of the Panel.