INDEED! Big thumbs up and my most sincere thanks to all who helped solve the mystery.
The Viper and the Raider are asymmetrical. That is reflected by the texture. To bring more variety into the model I coloured several panels in a different shade of grey. I may release a fully clean Viper, too, for those who want to weather their model differently.

The Viper and the Raider are asymmetrical. That is reflected by the texture. To bring more variety into the model I coloured several panels in a different shade of grey. I may release a fully clean Viper, too, for those who want to weather their model differently.
