What I did:
I dont like the factory Bose Amp..its dead/flat/boring. I did the same thing on my 05, as Ive now done on my 07, but better.
LOW LEVEL SIGNAL
I tapped into the Low-Level pre-bose outputs from my NAV headunit by soldering RCA jacks onto the ends of the low level wires. This was tedious. You CANNOT use side-taps for the low level wires as they will vibrate loose. I pulled all the pins out of the plug that goes into the bose amp, soldered the RCA wires to the pins, then re-inserted the pins into the plug. This is the most difficult thing. It provides me with FR, FL, RR & RL RCA signals to feed both of my Amps.
SPEAKER LEVEL:
Speaker level I used normal Side-Taps with crimped Male-Female plugs. Worked good on every car Ive owned. Ran the wires (as well as all the RCA's and Amp Remote Power on) under the carpet from the back of the center console, next the the drive shaft tunnel and then under the seat frame. This required complete removal of the seats. Not hard, but heavy. In order to get my Subwoofer in there, it requires seat removal anyway.
The Factory Plug for the speaker wires is simply disconnected from the Bose Amp - this is critical!!!
REMOTE ON:
Splice into the White Wire that goes into the Bose Amp on low level plug - I grabbed this at the Huge Main harness. Simple Male/Female crimped plugs. Dont use that wire, causes bad popping when turning on/off engine - instead use: http://chevyavalanchefanclub.com/cafcna/index.php/topic,136118.msg2054811.html#msg2054811
MAIN POWER:
I ran my 4GA (+) on the passenger side under the kick plates and up thru a small hole I did with a rubber grommet in the firewall passenger side. Needs about 12 feet. Have an 80-Amp fuse next to the battery. Connected directly to terminal bolt on battery.
Ground Wire is ran to a bolt on the rear seat frame, which is directly grounded to the truck's body via the 6 bolts. There are 2 13mm nuts between the big and small rear seats that are perfect for grounding to. My ground cables are about 16" long each!!!
Total Time: You dont want to know. But to do a job right, with nicely organized/unexposed wires with shrink wrap and cut to length etc, its whats required. All speaker and RCA cables were high quality, making them harder to run and to tie off and thread, cheaper wires are definitely easier to run, but sacrificed audio quality.
PS Notes:
0) There are 3 plugs into the Bose Amp (my truck has NAV Unit) - One plus is Power (+) & (-) and SUbwoofer Spkr Out (4 wires). The Middle Plug is 4 Door Speakers out only (8 wires), and the Passenger side plug is Low Level in plus Remote Power on for Sub and an Orange wire which is Data and basically unused?
1) The Low level pre-Bose signals are different than my 05, different colors, and different voltage. My 05 ran both (+) & (-) at +5.5VDC, my 07 with NAV runs at +0.1 to +1.5V AC (a normal low level signal)
2) With the 07 I found Im able to use the Low Level signal from the NAV unit to drive the Sub Amp, this was not so on the 05, as there was just no bass, instead on 05 I tapped into the Speaker Level Subwoofer wires and used a Line to Low level RCA converter. Dont need the converter on my 07!!!
Since I already ran the RCA cables for my Sub Amp under the carpet and seats re-installed, Im using RCA Y-Adapters pulling my sub signal from the R & L rear channel. This will Mute my Sub when the RSE is activated, and I can attenuate the Sub Bass by Fading to front if needed.