Should i get new speakers for my crown victoria?

i have a 1997 ford crown victoria lx, i installed a new kenwood stereo in it and it sounds great. Its volume goes up to 32 and i can put it up to 28 without it distorting. But I do have the sounded partially faded to the rear speakers. Should i get new speakers? I dont want to spend too much money on them and i dont want to buy new speakers and them just end up sounding the same or worse. Or will any new speakers deffinantly make it sound better?