An alternate to SP is B- or D-Prepared. The CRB is working on a new set of SIR sizes to better match the power generated by actual WC cars, which should make the classes more attractive for builders. Turbos and AWD are welcome, and you have your choice of 250 and 450 hp (soon to be increased). You also have the choice of Nationals or Regionals, and the same set of rules across the country. Stan