That is the most apple to apple comparison of the design itself. Showing that there is no gain in low end and mid range with the DESIGN. The gain at top is because he did away with the ease of install, the abilty to work on the car easy and the ability to bolt in stock cats. This allowed him to make the pipe have a little less bends to gain a little on top. To gain more low end the pipe needs to grow faster with smooth transition.