hey man, the stiffness of the spring doesnt really have anything to do with wether you need new shocks or not. Its how much the springs lowers the car. And even if it lowers the car a lot your stock shocks will work for a little while. Then they pretty much stop working and you car starts bouncing. Depends on how good the shocks are from factory. I have a friend with a '00 jetta he bought some springs that say you can use stock shocks with them. It didnt lower the car too much but with big rims and tires the thing looks damn good.
Point of this is, you can use stock shocks no problem but they will stop working sooner or later and you will need new shocks, but that may be 1, 2 maybe 6 month or more before your shocks go bad (depends on quality of stock shocks). Even if they do go bad, you can still ride around with them, I do!! ofcourse I just ordered new shocks, they're on the mail