Hmmm, interesting that there is such a wide range of experiences with the stock setup. Something must be different from car to car, maybe they used multiple sources for the springs and/or bushings and there is a slight difference? I'm glad my car doesn't hop, at least not on the street. I had a '67 FB that hopped like crazy with the monoleafs and factory bars and ended up putting helper springs and airshocks on it to get it under control. So I've been there.
06 Impulse blue, M6, 17"
69 LeMans vert, stock-looking 455-powered "sleeper"
74 455 TA, HPP magazine cover car