I'm sure all those recommendations work. But, i've used Easy Off Oven Cleaner twice. Once, on the muffler (when i bought the bike it had some melted boot leather on it), and once again just a few days ago. I had inadvertently dropped a micro fiber cloth (whilst wiping down the tank) on the header while it was idling and it melted on it like a plastic bag immediately. Crap! Some of it flaked right off, but had to use Easy Off for the rest with a wooden popsicle stick for scraping some of it. Worked like a charm. (Be careful with that stuff and don't get it on paint etc., whilst using it). I sprayed it on some cloth rather than straight onto the pipe.
