High lift valve spring set that is ideally matched to many of our street camshafts.  Our WBC518v2 camshaft was specifically designed around the characteristics of this spring set.
 
We manufacture hardened valve spring locating cups specifically for this valve spring.  When using spring cups it is often necessary to machine a counterbore into the cylinder head surface so that the spring cup thickness does not influence the valve spring's installed height and pressures.