Terry and I (mainly Terry) have been updating the flags and especially the RadarBox file that allocates the flags to the Mode S codes (D008.dat).
It seems to all work well, so here is a zip which updates them. Before anyone complains about wrong flags appearing, do check that the Mode-S isn't a miscode, which obviously can lead to a mis-flag. The zip includes a Readme file with detailed (very simple) installation instructions. (If you can install new logos, you can install this.)
This zip is also available on my Downloads page (click the blue globe beneath my username.