for the GS, a good set up is either a dual voice 12" sub such as a fosgate or kenwood in a sealed box centered in the trunk or if you want to completely fill the back area of your trunk, use two single voice 10" subs in a ported box. whatever you do, do not go with any type of bandpass box in that car, i doubt you have the need or the want to spend that kind of money on the power necessary to actualy require a bandpass setup.