The popularity of Soft Cores is rapidly increasing. Their integration in a design requires their synthesis and optimization, thus their application is more complex than the use of Hard Cores. However, Soft Cores can be customized to the design constraints, thus promising to lead to more efficient designs. The decision of using Soft or Hard Cores is difficult since it is a trade-off between performance, cost and design time. The parametrization methodology presented in this paper gives to the Soft Core providers the possibility of putting on the market easily customizable versions of their Cores. Moreover, the proposed Soft-Cores generator helps the designer to select between the Soft and the Hard-Core version of a processor.