It only comes with a crappy coaster, but if you get the steel one you can do whatever you want.
I made and welded a bracket to put discs on the front and drilled/reinforced a mount for a simple caliper on the back, but will eventually be welding tabs for a V-brake rear on my Hyper. Coasters suck and will kill you over 30mph. All it took was one close call for me to get rid of it (coaster skipped and jumped chain at 45+mph, would have went right into traffic if I didn't have the front BMX caliper installed as well...which was just enough to slow me down)
I was lucky thet the drop outs had the holes for this to work.The back piece of the mount sits on top or the drop out for a little more strength. View media item 60823 View media item 60824