if youre also looking at jl subs, go with them over mtx's.
that size amp should be more than enough. i have two audiobahn 10's and i only have a 550s punch amp. its not bridged and the gain is up and the bass on the unit is on -7 (lowest) and with a bass cd, you can hear the amp pushing the subs pretty hard. i am more than sure if i bridged it, i would blow up something or the subs would not last very long.
i would just get a regular car box, it should fit.