So here is a “how to” on removing the intake plenum on the 3.5L engine. A couple reasons why this would be done would be to change spark plugs or to access the lower intake manifold.
The procedure is not really hard but may take a few hours for the first time. Once you are comfortable with it you can probably remove it within 30 minutes or so.
My apologies for my poor photography skills and just ignore the boring stock and slightly dirty engine bay. It will be taken care of soon enough haha.