Goo Gone works great (probably the same type of product as Goof Off). Get the bigger bottle that has the spray top. Spray it on and let it soak for 20 or 30 minutes. On flat panels, a razor blade or putty knife will help scrape it off (if you will be repainting). You might be able to do it will a plastic scraper if you and trying to be careful with the paint. Towels work to get the last of the residue off. The previous owner of my car had a lot of stickers on the car and it took me about 8 hours between peeling and scraping to get it cleaned up.
I think the SRS1 is supposed to be a good product, but if you can afford it I would go with the HANS, Hutchins Hybrid, or R3.