Currently I am running a pair of infinity kappas in the front and a pair of alpine spr17c's in the back. They are connected to an alpine mrp f300 amplifier (it pushes about 200w). I want the mids and highs to sound better. If i got a subwoofer would it make the system sound better? I don't want the car to be rattling like crazy. My concern is with clarity, i want the music so be super clear. Any suggestions. Thanks.