Warpage

who told you that ? its a surface stretcher , how is that shrink metal . i have them , and it f...up the surface so bad there is no way to fix it nice , the metal is warped and needs to be put back in line not beat up . every panel gets stretched when it goes through the dies of the press , now you weld on it , it warps not stretches . some shrinkage along the weld , but no need for that aggressive hammer head . believe it or not you heat the metal then wet rag it to shrink metal , buts after you've worked it all out , so you can deal with the full areas . just how i've done it for years , tot by my father , he was a true metal man he never needed bondo .