This is actually a VERY big topic right now, i think the Camaro's biggest obstacle is the same as the Challenger's except GM has overcome it better, that would be having a 2-door car on a 4-door platform, you're just wasting weight in that scenario. As far as the engine goes expect an extra 150-200 pounds if its supercharged, another reason im not a big fan of supercharging the Z/28, id rather see a cammed LS7 putting near 600hp with less weight and a meaner roar
If people want a good comparison of what the Z/28 would be like supercharged then look at the GT vs the GT500, the GT is like 3500lbs while the GT500 is around 3850lbs? Hopefully GM will see this as a problem and take measures to overcome it, im hoping for lots of parts swapped for lighter parts, lots of emphasis on weight savings in the new Z, otherwise you might as well just supercharge your SS right?