These work great, first used one 20 years ago to remove pinstripes on an Acura Integra we were building.
For removing decals I use hairdryer (common sort found in your ladies bathroom).Just heat the area gently and peel off slowly.the decal comes off in one piece and takes the "gum" with it.And no!I don't nick my ladies dryer,I have my own......cos I make decals (stickers we call them) and use it foe that.