i've heard lots of good things about the twin power. some supras seemed to be plagued by very weak ignition systems and the twin power seems to remedy the situation. not sure how much of a gain you'd see on a bpu car, i've only seen the twin power on single turbos.
the itc is something completely different, the itc allows you to control your timing maps. i wouldn't get it unless you're fairly competent in tuning it. like a fuel controller, it can very easily do more harm then good.