I prefer to use 6.5" because you'll get better and louder sound (to small if you use 4" because you use 2x12" SPL sub).Do you use an amps to drive the speaker?I think you should get an amps to drive it.
Dynaudio, focal, Mb quart, a/d/s, DLS and Rockford Fosgate can be your choise.Depends on the...