I am only using steel Wool grade 000 and a good layer of WD40 to remove anything melted on exhaust. WD40 prevents formation of scratches while very fine steel wool removes plastic, tar, burnt oil.... I started to do that on my young 21 years old HD mostly riding close to ocean. Try this tip and you will be surprised.
I try to avoid use of chemical, and abrasive paste which does the job. But as soon as you start with chemical you have to go on polishing very often.