The Paul Revere and the Raiders tune, " SS396 " is viewable on youtube as well. There are lots of old commercials. I saw one once for this supposed never available option on a GTO (how dare I on a Chevelle website, right?
), where there was a vacuum-operated butterfly that opened in the muffler, to essentially dump the exhaust out before the muffler. That was cool, the guy was cruising a parking lot and opened it up.