I did seriously look into converting my SG windows using a spacer frame and inner panel. When I checked on the legality I was informed that both cab and hab glazing would have to be approved and marked with the official euromark. I was also told that acrylic and polycarbonate was not allowed, although there is a process (very expensive) to make poly acceptable. I did ask how Seitz managed to get approval, but did not get an answer. My info came from one of the UK's major vehicle glass manufacturers. Geoff.