well, for really tight turns (autocross) to prevent too much understear put the max. recomended in the fronts, and put a little more then usual in the rears.
the best way to find out if you need more air in the fronts, is to get a tire pyrometer, after the tires are heated up from many fast corners, check & see if there's a uniform temp. across the front tread, if the sides are a signifigent amount higher in temp then the center, you need more air...