90 is enough to stealth successfully every time. But the higher your stealth, the less chance of being revealed. I suggest 120 stealth looking at the rest of your template. There are tons of items that increase stealth as well. I wear a burglar's bandanna and shadow dancer leggings to bring mine up to 120. Also, the ninjitsu mastery, shadow, is incredibly helpful when you need to take a stealth step or 2 and shadow jump is not an option.