I want to see boost and oil temp, which I'm going to mount in the factory JDM gauge pod. I've got an unhooked EGT gauge sitting next to my boost gauge right now up there, but it's a somewhat useless gauge imo.
So boost and oil temp up high, and EGT, oil pressure and one other (?) down low.
Unless I've got a bright red blinking idiot light to indicate a sudden loss of oil pressure, a gauge isn't going to let me know in time that my engine is dry and fragged. They teach us to briefly glance at all our gauges once per lap on long straights just to monitor.