Every Whipple Supercharger W275AX (4.5L) pulley is made of 6061-T6 billet aluminum and anodized for wear and environmental protection. Each pulley is engraved with the running diameter size and state-of-the-art lightweight pockets to lower reciprocating mass as well as a guard feature to help unwanted belt wandering during hard running. Standard finish is hard coated black anodized. Dimension of each supercharger pulley is based off of the running diameter.
*A general rule of thumb is every .125" of pulley change is 1psi of boost.*