when u say 6 speakers u mean the two in the door, two tweets and the two in the rear doors? to be honest ur nto gonna notice much from the back unless u jsut want bass or u gonna do surround sound (in which case i been told u can get a centre speaker).. most SQ setups are front setup and fade the rears almost out so its like a concert environment with sound coming from in front of u.. if u got stock rear and a sub then ull be fine.