Box for 1240D MM subs

pentoncm

I am going to be installing my new polk MM 1240DVC sub in a .95 cu ft. box. I would like to have the sub dampened optimally for best sound quality. I have run the sub through the winisd program to look at box size and with the recommended .88 box it came up with a qtc of .95. In the .95 box it came up with .93. I was thinking of putting in a pound of poly fill in the box, would this be reasonable?