Well Im getting a 15" custom tc9 the guy who i bought it from (nsqm13) said that 2.2-2.5 cubic feet would be good for a sealed box. Mounting depth is around 8.5". So what demensions would be good? I was thinking 23x17x12. I don't really know. Want a good box design space isn't an issue at all. Well any help would be greatly appercaited.