u could try stiffening the back up to try to prevent the front wheels from lifting a little, as the weight gets transfered to the rears. other than that, a slight lift of the throttle, then steer, and get back on the power, should help a bit. it might well be worth tring some thicker oil in the centre diff, or even locking it. just try one thing at a time tho, or u wont see what difference each change makes.

for gravel i normally run quite a stiff setup with at least 60wt oil in the shocks, but i dont have a gs storm... same principle should apply tho.

oh - what tyres are u running?

hope that helps - i know how frustrating it can be getting the right setup.