Stabil core is woven for stability and I'm not sure if its carbon,then there's carbon backing witch is a special weave and lay up, not all is the same lay up and different thicknesses, it's used as backing, and unidirectional can be used anywhere in between, I like to use uni carbon right under carbon backing with foam cores and a bow glass belly.Lots of variables. It can make a difference with a good design and core layup, especially in a highbreed. Again experiment a little.