At the end of a strong year in the 1990 World Sportscar Championship season for Nissan's R90CKs, it was decided that the company would leave the championship to instead concentrate on the R90CPs in the All Japan Sports Prototype Championship (JSPC) and GTP ZX-Turbos in the IMSA GT Championship in North America. Regulation changes in the World Sportscar Championship would have required Nissan to abandon their turbocharged engines in place of newer, advanced naturally aspirated units, as well as design all new cars to handle them.