Carbon express rates their arrows opposite of Easton/ Beman. A CX400 is the stiffest shaft offered in the Carbon Express line (about a .290 spine). These arrows are extremely overly stiff for your set up. A CX400 would be the proper arrow to use if you were shooting 75 - 80+ pounds, had a 29"+ arrow length and were using 125 grain tips.

You should be using a CX 200 at 55 pounds. I figure with the whisker bisquit you arrows measure about 27 inches long and assuming the popular 100 grain tip.

You may also need to adjust your center shot slightly and your nock height.