I just installed the new chrome tow mirrors yesterday myself. I am going from basic DL8 mirrors on my LT Silverado, According to the service bulletin I needed the mirrors, 2 door harnesses, and BCM reprograming.
I bought all of the parts from various online retailers, all said and done with shipping I have about $700 in parts.
The hardest part of the install was removing and reinstalling the door panel. Removing the clips with the weather stripping to reinstall the panel can be very temperamental.
replacing the wire harness was very simple. It was time consuming because you have feed everything through tight spots, especially where you connect the harness to the cab. But as long as you pay attention to how the old harness is ran it is easy to figure out where the new one is supposed to be.
Mounting the mirror was very simple. The kit came with the 2 extra nuts for the 4th stud, so you reuse the 3 nuts from the old mirrors in addition to the ones included in the mirror package. Drilling the hole was very straight forward, from the inside there is already a hole in the inner sheet metal. A metal step bit drilled through the outside panel like butter.
To my surprise all of the mirrors new features work great without any dealer BCM reprogramming. The white cargo lights even work in reverse which I have read on here some people are having trouble with even after reprogramming.
All said and done the new mirrors add great field of vision and look great, I would think anyone with simple mechanical skills should be able to install themselves and save a significant amount of $$$.