From all of the setup info I've read the front springs should start just tight enough to keep the keepers from falling out and go from there.
I'm getting WAY too much body roll and inside ski lift so I'd assume I need to go a little stiffer. (Or get a bigger swaybar.) I also assume by doing this, I'll loose some bump compliance in the front.
Loosen them a bit and see how you like it. Most of the setup info here and at arctic chat.com shows that people tend to set up these ZRs way too stiff. Mine was and now with rebuilt shocks and softened suspension, it runs through the bumps better than my buddy's 02' XCSP. I only occasionally bottom out mostly on G-out type situations which it seems is OK. If you don't bottom occasionally, you aren't using all of our travel.
By the way, i ride a 99 ZR500.