I have tried a lot of these mentioned methodes, and most have left marks on my chrome finnish. I quite touching any thing metal to my chrome. I now use a cloth wrapped arround a putty knife with the pipes hot to soften the offending goo. Any of the mentioned chemicals and polish will take care of the rest.
Years ago I was a a motorcycle event and a couple gave me a sample of a product they were developing called Road Rub. It was in a thing that looked like a stick of deodorant. It works great on scuffs and even small scratches on windshields and paint. I ran out and ordered some a few months ago and I noticed that it is now owed by one of the big car wax companies. Guess it was as good as they thought it was. Just google Road Rub and you will find a number of retailers. If you have a shop, there is also a link to become a dealer. Good luck and ride safe (And scuff free).