I just got the Katzkins kit, but when I removed the headrest and tried installing the new cover, I don't have enough room to zip it all the way up. I zip it up about an inch and then there's not enough slack to finish it. Any tricks on how this is to be accomplished? I tried leaving it out in the sun, baby powder, squeezing it like crazy, duct tape. Compressing it with a vacuum caused the foam to shrink for a few seconds before expanding back into normal. Anything short of cutting back the foam would be fine. Both headrests had the same amount of lack of space. Even the old headrests won't go back on.