Good question petraidm, I was wondering the same thing.
I recently ordered Souveran paste and put 1 coat on my electric blue Acura. As we know it does darken the color while giving a really nice 3-D shine. More coats I'm told will further enhance this look.
b-max . . . what was your experience with the Souveran vs the Sig Series? Do they look the same - darkening, depth of shine, etc.?