I never was a huge fun of the pipe design that you and Anthony looks like embrace. There is none contestable topological advantage that the pipes might be aligned in a curve to make a very perfect time alignment. This is given. How practical it is I do not know. I think it need to be aligned one pipe a time, starting from the bottom during the pile assembly… Another point is the sharp rollback from the back wall. The pipe design will have a permanent sharp enclosure mode deriving from the one single reflection surface. The pipe des has it as well but there are many reflection surfaces and the modes are kind of defused. With the pipe I think the reflection mode should be only one and it should be more prominent than with box. Saying all of it and understanding that you have good 2 inch foam in the box, or perhaps 4” in the back wall, not to mention that you guys run it all at very LF it is possible as well then my comment about reflection mode are purely theoretical and will be negligible in practice. I never experiment with pipes and do not know what work in them and what is not.