I was going to give you some heat about that stove pipe and say that the wall looks great.
Single wall stove pipe must be 18" from combustibles and that includes the sheetrock paper or the wood mantle. Double wall stove pipe requires 6" to combustibles and is what you should be using if you can get the 6" even. Class A pipe only requires 2" but that is what you would use beyond the ceiling or wall penetration.
You will like the double wall pipe, it is two walls of stainless steel and will last the life of your stove, or at least as long as a new stove would last.
I recommend NOT using a magic heat device, they are creosote and chimney fire magnets. Better to burn your stove hot enough to make the heat you need.