vvt-i
used to only control the intake cam, because it generally made very little difference when added to the exhaust cam (I believe as exhaust valves/ports are generally larger anyway). Maybe they've found a way for it to make a larger difference, which is why they'll be adding vvti to the exhaust cam on the FT86 too?
From what I've made sense of, vtec uses a camshaft with two different lobe sets for each cylinder, and the used lobe set is changed at a certain rpm, where vvt-i uses a camshaft with a single lobe set for each cylinder, but instead uses a variable gear to change the gearing on the camshaft to essentially lengthen the timing, allowing more flow.
That's only if I've got the concept right though.
