We are finishing our walk out basement. It already has 2x6 walls filled with cellulose insulation. Some of that insulation has settled and left voids in the wall. I am going to need to insulate some new walls anyway so do I pull all the cellulose and spray foam(open)? Or just repack the cellulose with some more and move on. I want it warm and air tight. It is a lot of wall 100+ft of exterior wall. Will I see a benefit....enough to justify? I regret not doing it foam the first time.