I believe the low was 655.6 yesterday. It should be the key support or strong support, with 656 as the weak support. If it breaks that level with strong downside volume, definitely this key support will break. For now, with very weak volume, just play this trading range.
For now, it is trading between 656 and the 38% fib retracement 657.4.
For stops, I put below the key support when I am long, I put above the pivot when I am short. On exit, most time, I exit at the key fib retracement levels.