So I am going to stuff the riser with insulation tomorrow. My riser is about 8" high and has 3 1/2" holes cut in each of the bays so there can be some bass trap action. Behind the holes are some loosely fastened squares of mass loaded vinyl to prevent mid and high freq from getting absorbed.
Should I use R30 paper faced insulation and fasten the flanges to each of the joists so that is will gently touch the floor, or should I just stuff it with insulation?
Picture below of the riser with cavities and holes.