*The step 1 cam be used to work with stock valve spring rate, no modifications required for a true bolt on item. **HKS Step 2 Camshafts Require HKS Valve Springs (2201-RN011) ***HKS Step 3 Camshafts Require HKS Valve Springs (2201-RN011) and HKS Lash Killer Kit (2499-RN001)