im thinking of getting new speakers front and rear and a new head unit. no subs but am wanting good bass. a friends car has some really good bass coming out of the back.cant see the speakers they're strangely hidden inside the parcel shelf 0.o

im not too sure if they actually produce words when the songs playing for exmaple, more so just the bass? is that possible?

anyway just wondering what kind of setup i could get if im wanting good bass with just speakers front and rear and a head unit, are there types of subs that are speaker sized and can replace the rears for exmaple?

any help much appreciated =D