Pull apart pie chart slices in Illustrator but retain stroke

I have a pie chart created using Illustrator CC's Pie Graph Tool:

I want to separate the slices to create a gap in-between. I see that this has been asked and answered before, but the answer causes a loss to each slice's stroke (gray becomes white):

Is there a way to add the dark gray stroke back onto the slices? I know that technically they are not actually separated, so must they be ungrouped or something first?

Thank you.