SMiller

Lots of vehicles come factory filled with synthetic...

This ABS and Stibilitrac have almost caused me to crash on ice, I needed more aggressive braking and needed to steer the truck but abs so nope you will have no braking and damn sure not going to turn the truck to avoid hitting something. Remember when you could use the throttle to steer and could actually drive a vehicle?!?

Confirm, can also include the 5100 in their. BUT we are talking the old generation trucks and not even close to the current trucks. The '01-'10 HAD trucks had shorter then stock Bilstein shocks. The 5100 shocks that are supposed to be for leveled trucks are the exact same length as the factory shocks and require a spacer, otherwise you are trying to rip the shock in half when you bottom out and you are not in the correct valving of the shock, once spaced it let's the frame stop do the job of bottoming out and puts the shock back into the correct valving, giving you full travel and the correct ride. 5100 are great shocks, no they are perfect shocks, just remember to add spacers if you run cranked torsion bars.

This I use fishing line if it is stubborn. GM installs them crooked, they peel off, they fade, or they bubble. Worse yet is they hold moisture, dirt, and salt behind them. Best to remove them and trow them in trash ASAP.

Wiring harness is on your truck already, if you look up behind the bumper you will see it, it would require a flash of the BCM and new bumper so not worth it though. As someone else said your truck came with snow plow prep, 220A alt., and dual batteries all as options not standard or included with snow plow prep although it does include the larger alt.

You are way overestimating the Stibilitrac and G80, G80 goes back to 1 wheel peel over 30mph and even Stibilitrac says no go when you try to do a donut. When I am in deep snow I need the truck to dip and slide to find traction, I don't need Stibilitrac fighting me the whole way.

G80 good/traction control bad... I shut off traction control/stabilitrac as soon as I start the truck.

English?

This. Driving down the road with a plow raised is no longer a issue as the trucks are so tall now that the plow doesn't block the grill, still lots of airflow. It would take a deep deep snow in a small lot to get the trans hot. Having said that it can only help to drain and fill once a year as it only gets about 1/3 of the fluid out.

Is that 15-20hp across the band or at peak rpm? I have seen many dynos with cold air intakes that show 22hp gains yet they are down power everywhere but the specific small spot where there is a gain. Fakenews... I am a header fan but a small cam L96 that doesn't spend much time in the 4000+rpm peak power rangers I just don't see making huge gains where they are needed.

In a motor that makes peak power at 4400rpm... You need them deep gears in a gasser!

Leave it be, how often are you truly at full lock? Even then it makes zero difference, wheel spacers come with their own headaches.

How much power is gained with headers over a stock tuned 6.0?

Yes

Unless you are going to cam and tune you are wasting your time.