Could you explain a little bit more about the SOT-976 connector. I love the idea of keeping the factory wiring stock. I am doing a very similar instal with one of Nicks uberstealth boxes, and my original plan was to tap the signal in for my subwoofer from the rear speaker harness close to the hatch, similar to the way Veeedubme did in his build. Now im wondering if this may be a better option. Did you just splice into this aftermarket connector near the HU?
Also, how does everything sound with out an amp on your 4 new component speakers, as this is what I was planning on doing. Right now my issue is the loudness of the stock non-dynaudio RNS 350, I just cannot turn the stupid system up with out it completely distorting everything (even with bass turned to -4)