I just watched his build on you tube its a good looking stove and great for a first attempt, he says he is planning to move the sec air on the next one to the opposite side in order to increase the vortex. Wont really have the desired effect though because its quite a passive effect. when entering the riser it ignites the gasses, and the best placement for this is where he has it now from all the tests i did early on, but i never had temps like the ones inside my cast riser now so placement is maybe not as critical but still better for mixing with the gasses.
That big firebox is great I had thought a front loading door was the key to a bigger firebox and im glad he went this route and proved it. But modular wins out over welded and if i built a larger firebox it could be simply bolted on the front. I stress I dont need any more heat but a longer slower burn would be nice to calm my stove down, plus i wouldn't need to gut the logs so small.