I am new to this forum thing. I saw your post and I knew that I might be able to help.
We have been using these headers for a couple months. My loop installers really like them cause they save a lot of fusing in the field and they save a bunch of time. My installers have noticed the purging seems easier and faster. I would imagine that is because the flow is balanced? My boss is happy cause he knows that the reverse return screwed up.