What is CMIIW?? MIVEC used to be for high revving NA engines like the 4G92 MIVEC and 6A12 MIVEC. But recent new ones are more towards better fuel consumption like i-VTEC. For Evo, I think the MIVEC improves low end torque and fuel consumption.Yes, starting from Evo IX, the head got MIVEC already but in the IX only for intake side, while for the X if I'm not mistaken already for both intake and exhaust (CMIIW though coz I don't really pay attention anymore to the X). The MIVEC actually should make the engine more powerful and responsive.