I recently got a garrison 1 stove and it has a 8" rear pipe oulet. I was considering reducing this before it leaves the house to six" and then running with that size chimney pipe all the way up to the top of the roof, or should I just stay with 8" all the way. Will there be all that of a difference between the two. This is going to be a brand new install so the difference between 6" and 8" is pretty significant. Thanks