mivec is much like vtec. mivec was created before honda came out with VTEC, but honda used vtec much more widely then mitsu, and they did it in the states, while mitsu didn't feel we needed for some odd reason. most of today's mivec systems use direct fuel injection (which owns all other forms of fuel injection) and 3-staged cam lobs (compared to hondas two-stage set-up) that are used in three different rpm ranges (1: 0-3000rpm, 2: 3001-6000, 3: 6001- 9000, this is just an example). but the mivec itself is just the staged cam lob system, that's why you can use a vtec controller to manipulate your mivec engagment in the same exact manner.

this is my understanding.

Mitsubishi really made vast improvements on direct fuel injection technology for the industry, and their DI system runs on a sick-as-fuck 700 psi of fuel pressure that's produced by an engine-feed injection pump. coupled with mivec, you can extract massive amounts of HP and super-efficent gas milage with direct injection.