I don't know how much an 80/20 batt will shrink. I also don't put my quilts in the dryer. They seem to end up in a big ball so I line dry them. I use Warm and white batts and I preshrink them by putting them in the washer in hot water and letting them soak. Then I just spin out the water and put them in the dryer. It will shrink before I quilt it but once it's quilted, I don't put quilts in the dryer.