I believe that both the racing Panteras and Mustangs get down to 2,850 , which is the class weight rule? If you go under that you need to add weight to get to that.
New systems expected on street cars add weight. I think "911"s are even in the 3,300 weight category?
I think that my Audi TT is 3,200?
I wouldn't worry about the curb weight unless I was going racing. The C8 already has an aluminum frame. How well it preps for racing remains to be seen but perhaps there will be an "R" model like the Shelby's offered at some point?
I'd expect a lot of carbon fiber replacement parts available either through Chevy directly or through the "back door"/aftermarket. I'd think that a factory "R" model would be somewhere over $150 thousand though.