Hi Mike, Just a little word of warning, I've owned two GV's, both apparently 2004/2005 models with the same amp and infinity sound system, RB3 head unit, however they were both very different when it came to the speaker outputs from the RB3. As per my website investigation/link the signals appear to be digitally encoded onto the 'speaker' outputs from the RB3. (I'm planning next summer to spend some time on this, and use my oscilloscope to interrogate the output from the RB3 speaker wires) All I'm saying is, don't assume that all models are the same, there are clearly very subtle differences as I found between the years (1 year difference in the ones I've owned!) and in some cases you can't just splice into the speaker wires as it just won't work.