Yes that helps a lot
My guess is that the metal flake (usually aluminium or brass) is not dense enough to shield the signal. I know someone over at Dupont and I think I will ask them if they have any technical information on this. The fact that yours is very similar to how mine will be is very inspiring, and I'm glad that you had such good luck with that mounting location. This week I will buy a density meter and see what the differences are between regular metal flake and the metal flake that will actually be on the car. I will be fabricating a custom fascia for the laser heads, so if I can't mount the radar head behind the bumper cover then I could always include it to fit into that fascia. How high off the ground is your radar head mounted?
Some have claimed that Ka performance can suffer when mounted by a bumper cover
What are they basing this on?