HKS camshafts are not reground OEM units; they are machined from new billet cores which are constructed from a high nickel content iron alloy. By manufacturing all camshafts from billet cores, HKS is able to produce camshafts that equal or exceed the quality of the OEM units they are designed to replace. HKS camshafts are direct replacements and are designed to be compatible with the factory valve train components.