Wiring 2003 Humer H2-wiring-diagram-ken-3.jpg

I have just started to install a new system in my 2003 Hummer H2. I have installed a JVC KW-NT3HDT head unit, a Focal Solid 4 amp for front & rear speakers, a Focal Solid 1 amp for Sub, running Focal 165 KRX2's in the front, haven't picked my back yet thinking about Focal 130 KR's (any suggestions), Sub is Pioneer TS-SW310. I have included a Sketch that I did for reference.

Now to my Questions. I have been told by a few different installers to disconnect the factory amp and others told me to keep it installed using the GMOS, and one told me no GMOS just to wire the factory amp with a hot wire. I'm have been very misguided on this issue. Can anyone please help me on which way to go, or explain the reasoning for each method spoken about. What way should I go. I have the knowledge and all wiring diagrams to make any chances just not sure which way to go.

Thanks Ken