So being an Engineer I know that there are always trade offs made during the design process. Many times in entry level consumer goods the choice is towards reliability over performance. Especially items that are meant to last 5+ years as our stoves are, I am assuming this because I have a 5 year warranty on mine. After reading here and finding a couple of white papers on combustion in residential woodstoves I have learned a few things. First is that for secondary combustion to occur reliably you need to keep up temperatures in the firebox. Their are all couple of ways to do this, provide increased primary air, this is at the expense of burn time. The other way is to have a better insulated firebox. This is what I wanted to address. Insulating the firebox better. The Avalon Spokane/Lopi Republic uses standard fire brick. The design appears to favor durability over performance knowing insulated firebrick would need to be replaced every other year if not every year. Detroit has a great number of companies that sprung up over the last century to service the auto industry. Among them are a few foundry builders. I have delt with one previously and called them up to grab some IFB. They were $2.20 for full brick or $1.10 after I cut them in half. After this I replaced all but the floor of the firebox with IFB. So the total cost for this idea was $16.00. Looking forward to being able to close the primary air down sooner and even a little more than I had been doing. If my understanding of the papers I have read is correct.