I've an '04 1800 n with Honda saddlebags, not sure on the volume, only size offered for the '04 n from Honda. There are three offered, plain, studded, and some with fringe but they're all the same volume I do believe.
I just put the cobra "swept" passenger floorboards on a couple of weeks ago. They look really good up or down. Not sure which model bike you have but if you gimme your email address I'll forward a couple of photos.