Much more usually a hybrid conversion using an RB30E block along with a twin cam RB25 head without a turbo is also used as a foundation for your RB30DE. The RB25DE cylinder head with the A31 Cefiro C33 Laurel or R32 Skyline (aka: Non VCT) may be used. The RB25DET (through the R33 Skyline or C34 L