first off, we're not gonna help you until you post pics
welcome to the forum. i think you'll easily find that an add-on sirius unit will provide more functionality than the OEM head unit. however, i think the issue you'll deal with is the same as adding an ipod. you'll still be stuck with using a horrible fm transmitter or the unamplified aux input to play through the stereo. definitely look for a unit that's got an inline amplifier so that you at least get a lil more umph before hitting the aux input.
welcome to the forum. i think you'll easily find that an add-on sirius unit will provide more functionality than the OEM head unit. however, i think the issue you'll deal with is the same as adding an ipod. you'll still be stuck with using a horrible fm transmitter or the unamplified aux input to play through the stereo. definitely look for a unit that's got an inline amplifier so that you at least get a lil more umph before hitting the aux input.