RE: New Red Bull Body
Well if you used regular white behind the pearl then you did back it. I just back mine a bit heavier I guess. I do like the translucent look you got with the lighter backing. You might also experiment with other backing colors. Something like a silver may have made the pearl even more noticable. Or maybe a pink and a blue would have given that Mother-or-Pearl look like on the inside of shells??
There's a lot you can do with paints like layering, mixing colors, different backing colors, etc to get some really awsome effects.
Also, with the decals, if you make a reverse image you can apply them to the inside of the body and use them as paint masks. Here's an example of what I mean. I had a buddy make the Harley shield out of vinyl and used it as a mask. The pics are not the best but you'll get the idea.