Yes, a horn works best when as much cabinet space as possible is devoted to the horn and not to the driver/rear chamber pushing it, so smaller is better as far as the driver is concerned. But getting the requisite driver specs won't allow you to go beyond certain limits. I can get what I need for pro-sound from a ten, but not an eight. I can get what I need for HT/Autosound from an eight, but not a six. That's not to say that these size limitatations might not go down someday if, again, someone comes up with a four that has a six inch Xmax and will stay linear with 300 watts input. I'm not holding my breath on that one. But even two years ago an appropriate eight for a horn loaded sub wasn't really out there, and now at least one (MCM 55-2421)is. Thanks to this driver I now have a horn loaded sub that is not only 10dB more sensitive than a ported box loaded with a 15, at 3.3 cu.ft. it's smaller too.