Well with there being 3 subs, it is most likely going to be a decent sized enclosure, so it will probably need bracing of some sort. So you might as well go seperate chambers. Thats just how I would do it, there really isnt a wrong way.
Any time I build an enclosure that spec's Kicker subs, I always do them separate chambers.
I don't know what it is about kicker subs, but they suck azz in common chamber enclosure's and I've heard kicker subs separate vs common and they just sound better separate.
