your speakers are shot, that pop is the universal sign that the speaker has had better days, the bose system is actually pretty good for a stock stereo, if it's sounding bad it's time for a total overhaul of the stereo because finding a suitable replacement is not going to happen. any speaker can be tossed in and it will work, but the bose system was tuned by engineers to sound it's best with the original speakers that most likely haven't been made in years