My speakers in my 92 325is are not that great for lack of a better word the back speakers have no bass what so ever and even if i put my subs its sound like crap in the back even when outside the car. i know that there is a factory amp somwhere, is my amp dead or sumting and if so how do i tell o and even a better question where the hell is the amp???

almost all stock speakers suck :)

amp should be in the trunk, behind the carpeting on the driver's side.