Wow! I just removed the registration letters off boat I just bought and it left some stubborn residue. I have tried both goof off and WD40 already and it will not take the outline of letters or all the rest off. Crazy stubborn. It's almost light enough I can just put the new letters over top and you would never notice but it would drive me nuts. Thought maybe it was due to being so cold where I am now. I could use the dryer again to heat up the area and see if that helps.