I'd like to point out that I've pursued this idea due to my ultimate goal of finding a simple install that is not so intrusive as a 3-way or 4-way setup yet doesn't need a $1000 processer; i.e. Pioneer's new P99. I currently run a CDA-9887. I'd like to stay within the confines of its DSP capabilities. This concept should be applicable to any vehicle. However, due to different OEM locations you have alternative solutions that are arguably better than what the grand prix offers.