These stiff spring comments remind me of the old 'California tuneups' we used to perform back in the day...I think I mentioned this here before?.
In retrospect, not a great idea but we'd pull the main springs and stretch them removing a lot of the stiffness for easier throttle application..
Customers were never told what had been done but always commented on the smooth operation and how responsive the cars were even under light throttle application!.
So if you come upon any of the stretched springs, sorry?.
~ Pete