There are also tweeters in front doors by the wing mirrors but don't really need them as the 4.7" Sony xplode speakers in the doors have built in tweeters. I really want more bass and I have a pair of boxed jvc 6x9 speakers that I'll put in the boot of the car.. Do I need an amp or should I disconnect the back speakers and use the 6x9's instead? Or will they fit in the doors? What will be the best sound without spending to much! My head unit is a Sony 4x50 watt by the way