I am looking into applying an extra layer of insulation to my west facing double garage door. The door is about 2" thick so I am assuming it is an "insulated" door already.
got any recommendations on what type / brand to use and opinions as to whether it is worth my time?
I have been looking at the Owens-Corning kits.
"Semper Fi"

insulating the door further will increase its weight so you will have to make adjustments to the helper springs. 2 inchs of insulation that you alredy have should be enough, unless you live in a really frigid area and spend a lot of time in the garage. I would rather invest in a heater that you could turn on when it's needed

It's not the door itself that's loosing the heat.
There is no thermal break in the metal frame so it transfure the cold inside, there's open seams between the panels, a really big air leaks on the ends and bottom. So adding insulation to the panels will do 0 good.
Check the seals on the bottom and the trim on the outside is about the best you can do.
Is the ceiling insulated and covered with drywall?
Did anyone use expanding foam around the window and doors, insulate the walls and sheetrock?