About the only problem with the stock springs is they tend to sag when they get old.  It's cheaper just to go with aftermarket springs to replace them, and you get the better peformance from slightly stiff spring rates.  Excessive sagging, especially at the rears, can induce bad alignment changes; lowering the rears below 1" can induce negative camber that cannot be dialed out.
Springs Mods Page

Questions?  Comments?  Send mail to:  reted@fc3spro.com