I used easy off oven cleaner on my chrome pipes. have to warm up just a little. I am not sure on black pipes though. hopefully someone can verify on black pipes.. good luck!
when the bike is cold, use gasoline on a rag, it wont hurt your chrome, and it will take it right off. I use it to remove road tar also. Did I mention to do it when the bike is COLD!
Go for a ride, get the pipes good and hot. Get back home, put on a welding glove and run your gloved hand over the rubber. The rubber will stick to the leather glove not on your pipes.
Let it burn off for awhile. The lady keeps leaving melted boot on my pipes & I used to freak out . Better to leave it for awhile before attempting to remove.
When hot, use a popsicle stick or paint stirrer stick to scrape off as much as possible. When cool, use some 000 steel wool with 'goof off' solvent (home depot).
I tried the oven cleaner, etc. didn't work for me but the above does.