The mono mix on the original THX 1138 was great, and then Lucas replaced it on the directors cut with a bogus 5.1 track.

Also the original graffiti mono mix is nowhere available on video, or the theatrical studio cut. The video cut before the cgi was the same as the theatrical re-release. I know American Graffiti was always intended to be mixed in stereo but the initial release was in mono.

I also believe the so called theatrical cut on THX 1138 on laserdisc and vhs has scenes that were restored for a re-release or on video, the original had trims done by warners.