msycamore said:

Another thing not related to THX, but I choose to ask it here anyway, any idea why the opening and end titles on American Graffiti is window boxed on LD and DVD, thick black bars at the side of the frame. Does it have something to do with the Techniscope format or was it just a way to avoid overscan on old TV's? is the Blu-ray also window boxed on the end titles and the opening Universal logo?

IIRC, it's to avoid overscan. I've seen an old movie or two that were windowboxed all the way through as well. It really shouldn't be needed on Blu Ray, but we all know studios sometimes use an HD master that more than a few years old.