When I bought B3820 #48, very used, the PO had taken the bonnet off and
fashioned a reverse scoop and painted it in primer. I left it off the car, and
found a special interest car boneyard in Lakeville, MA that had a fairly
straight black Alpine V with bonnet, so that one is now on my Tiger. Neither
bonnet shows any signs of insulation. As to whether Rootes sound-insulated the
Tiger bonnets, they seem to have provided plenty of sound, but not much
insulation, if the rest of the car is any indication.