For what they cost they should come with a coating.
Mine is rusting too but I'm not going to do anything about it right this minute until I have to take it off, then I'll paint it black and put it back on.
They don't need to be balanced, they are neutral. The old crank pulley needs to be balanced with the BHJ so they are neutral, but I used new underdrive pulleys that came nuetral.
Also having to hone the thing to get it to fit, and go buy a long bolt and washer to get it on, what a pain. It was however easier to make it fit and install it than it was for me to get the old broken stock one off.