While your pipes are hot, use Chrome Cleaner. The rubber will come right off.
My wife uses this method on her V-ROD with no problem. She consistently marks up her pipes with boot material. She cleans the pipes after almost every ride. Do not use anything abrasive including steel wool, brillo pads, wooden sticks, etc. You risk scratching the chrome which, once scratched, can't be undone.
Use Chrome Cleaner and a little Elbow grease. Also if using it on hot pipes use a heavy cloth or a paper towel folded many times. They are REAL HOT you know.