Neal is correct, you never want to compress fiberglass insulation. Stuffing more insulation into a space will lower it's "R" value. If you have the insulation removed, weather seal the outside by caulking any area that will allow air intrusion into the house envelope from the wall or attic. Seal where any wires travel up through the top of the wall plates, water lines exit an outside wall, missing caulk around window and doors. Any place that will allow air movement. More insulation in this case will not be a benefit and in effect lower the "R" value in the wall.