and apparently not all of the blue cars include that grille, just the early versions...all of the Camaro kits have the rare Chambered exhaust system that a lot of the owners complained were too loud, and also only have the headers, no manifolds, the Z/28s (the small block cars) have the cross ram intakes which AFAIK were not factory installed, but were a factory piece. They have no other induction system in the kits other than the BB cars. I believe builders are getting around the short comings using the exhaust and induction system from the Revell Nova kit.

I've included a link to the Muscle Car Modeler on youtube who details the differences in the versions.