What is the best way to weather a die-cast model? I guess one would have to spray the entire model with a matt finish, first, right? I will like to keep the original paint but tone it down a bit and add some pigments. So i would appreciate it some advice please.

You don't need to dullcoat it first. Take a look at some of the auto forums, they get some great, weathered looks out of gloss finishes. You can use the same techniques on them as an armor piece.

Thanks for replying but it sounds pretty unsual to paint or add pigments to a shiny glossy die-cast. How does it adhere to the surface without falling off or in the case of painting, stay on smoothly?

Also i could not find anything regarding this in the suto forum. Got a link?