About crossovers, we stock assembled circuit boards using a variety of optional components. You can choose from Jantzen, Auricap, Mills, etc. We also sell unpopulated crossover PCB's if you'd rather assemble your own.

About the midhorn, PaulW wrote to me some time ago when he was assembling his. He was concerned about how to mount them in the box, wondering how to trim them out. I suggested a hardwood trim that serves as a sort of edge band. The idea is to cut it to have the same angle as the flare. It is attractive and it extends the flare slightly, which isn't a bad thing. I think that's probably what you're talking about.

The midhorn is designed to be as small as possible without sacrificing sound quality. Even still, they're fairly large. Making a horn larger isn't generally a problem, it's making it smaller where you'll run into complications. You could make them larger, if you wanted, but when used in the corner, the walls tend to act as flare extensions anyway.