Pete,
I also have the Vivid Black Nightster and like you I am looking to get more black and less gray and chrome. One idea that looks great (to me anyway) is to paint the air cleaner cover. It doesn't take much time at all. You will need the correct size hex head wrench, and I just used some high temp flat black enamel paint.
I got the idea from looking at the sportster gallery, lots of great looking bikes in there. Have fun.
Lee
I have been told to use S100 Engine Brightner and apply it to cover. I have ordered some and will let you know the result. (the photos i have seen look good ).