Greddy R-Spec. cores feature a high heat-dissipating "Inner fin" design. This is ideal for medium to high boost levels on higher horsepower or upgraded turbo engines. The larger internal surface area provides superior cooling efficiency for radiating excessive heat and minimizing heat soak. Some R-spec. kits are labeled "HG" or High Grade; these kits feature piping and end tanks that have been hand-polished to a mirror finish for the ultimate in show quality aesthetics.