My panels have faded on my Lsi15's and polk was to the rescue. Read this thread for details...
Amazingly, I just now got to taking the old panels off. They came off pretty easy. They were just held on by this double-back tape-like product that came off if you stretched it. You kind of pull it towards yourself, and up. Kind of makes me thing of the 3M product that you stick on the wall to hang stuff on but you pull this piece of tape and the hook comes right off.
Now that I have the panels off today, I'll be applying the new panels tomorrow. But, these speakers look damn sexy now with their panels off! Slender, shiny, piano-black all around. See for yourself. It'll be hard to cover them back up ;)