All King basses are made with maple and/or spruce plywood. I forget which model Justin has, but they're all made with plywood.
And I know you asked Justin about intonation, but I have a pretty good tip for it, too...practice without looking at your neck. I used to turn off the lights in my practice room until I tripped once and collapsed my bridge

Now I just turn my head away. I play in tune way better without looking at the neck. Also, if you're playing a song or an exercise, stop at random points while you play and check your intonation against your open strings. That, to me, works even better than a tuner. Tuners can be annoying.