Are you putting it in the basement? The jacket will wash the sides of the stove and gain more heat from the stove, I have a LL hyfire in the basement and it could use the jacket to push more heat upstairs (this falls project), without it, keeps the basement nice and warm too. But I know I can get a lot more heat upstairs with it. It all depends on your situation. If you have enough air flow upstairs, you may not need it.
yes it goes in the basement, in my mechanical room. i want to pipe it into the return side of my furnace. is there many people out there that have used LL's hot air jacket/pipped into the cold air return and been happy with the results?