The GFX package on the Dale Jr. Camaro was painted CGM to match the top half of the car. Compare that to the yellow SEMA Camaro and you'll see that the yellow one has the stock dark argent metallic finish. It's not as shiny as the painted GFX pieces on Dale Jr.'s car.
IMO, I think the unpainted GFX kit looks blah. Rather then blend in with the body, it stands out. Kind of like what they did with the lower panels on the Challengers to make the body not appear as slab sided as it actually is.
If I were to get the GFX package, I'd make sure it was painted to match the body, regardless of the color on the car.