Go with the Eric said, I used them in the body shop and they remove the sticker and the glue.
The 3M one is 10-15 bucks CDN, use and electric or cordless drill (doesn't have to go 100mph)
Just remember heat is japanese steels worst enemy, so don't sit in one spot to long, it can actually burn paint (exteme cases)
Be careful using chemicals like acetone, if the paint is lacquer or enamel it WILL RUB OFF ( not factory paint or low quality repaint) do a test spot first.
Hope that helps
Steve.