I have a Traeger classic which I purchased from Costco years ago. I had problems trying to keep temp and even getting it up to temp. So I changed controller and that helped, but it still wanders, and outside temp does not help. It is single sheet metal. So I looked at other grills and started incorporating their features into this one.
First, I drilled holes in the heat deflector and it helped tremendously. The temp would get hotter and stay more even. But I noticed that the temp sensor is not really in a prime location. So I put one onto the grill and noticed a 50-degree difference between where I was cooking and where their sensor is. Thus I turned the controller up to compensate for this and put the temp where I was cooking at the exact temperature. Boy did that help.
So now I am moving their sensor to be portable and attach to the grill where the food is cooked. Next, I am lining it with insulating lightweight refractory brick, like in the brick ovens. Over that, I will put a ceramic coating, and then a stainless steel inner shell. Thus I will have a totally insulated inner cooking chamber. On the swing top, I am putting some insulation with a stainless steel inner shell also.
Then I am making a stainless steel deflector plate for the firepot with placed holes. The fat collector plate is going to be made into three pieces, with the middle one replaceable. the outer two will have holes in them, but with a cover, that be put over them. Same with the middle, but the cover will be able to be removed. by doing this I can use it to sear also in the middle. The other two parts will act like infrared heaters and give off heat. I have played with this a little and I can get it up to over 500 degrees for searing without any problem.
And finally, I am drilling out the fire pothole and placing a sliding gate of stainless steel over the hole from underneath. Thus I can just pull the gate, dump out the ashes, and get ready for the next grilling without having to disassemble everything.
When I am done I will have a super Traeger like no other grill and have the same features that $8000 grills have. I will be so well insulated that I expect it to use about 1/4 to 1/8 of what it is using now for pellets. With the mods I have already made I noticed I am using much less, probably about 40% less already. And it can now get hotter than it did before.
And then finally, I am going to make an extension for my pellet feeder box. It is small, but by building a nice stainless steel extension I should be able to hold about 3 times the amount of pellets that I do now. I have to decide if I want to make a hole to change the pellets out or not, but I do not really cook with a lot of extra mixtures, I seem to stay with one kind most of the time.
I am hoping that in the dead of winter that I can cook easily, and maybe do to or three-day cooks without having to refill pellets. The outside of the cooker is painted and holding up really good, albeit it is not stainless steel.
But some small changes to their "design" should help most people. Drill holes in that deflector plate (not above the pot, but around the outside, and think about moving their sensor and putting another sensor at where you cook to check the accuracy of their sensor. Do not think you can really hold the temp with their single-wall design in many states because of the outside temp fluctuations. I guess one of their blankets would help. but they never made one for my model.
But with the mods I am making for this one it will be a keeper for many many years, and even maybe a hand me down to my son or daughter.
The nice thing about stainless steel ( I will use 304) is that it does not allow heat to spread very readily and holds onto the heat. It does remit it as infrared heat. So it takes a while to heat up, but acts like this great heat sink and stabilizes the temperature inside. And the firebrick I am using is a very good insulator and also very light, so it does not add very much weight to the grill. The stainless is another story altogether. It does weigh and adds weight to the grill. I only need it thick though for the (12 gauge) for the heat deflector, and thinking about 16 gauge for the sidewalls and bottom, while the fat-grease tray might be 14 gauge.