You can call it whatever you want, but in my experience on my stock 22RE an opened exhaust that reduced the backpressure too much in the exhaust system definitely decreased the low-end torque.  During my face-to-face conversation with a Doug Thorley engineer for about 1 hour, he used the word "backpressure" at least a dozen times and he was specifically referring to the DT Tri-Y design.  He also referred to scavenging, pulse waves, velocity, and exhaust gas temperature and density.

Same issue when I went with headers and a high flow cat and muffler(at the right angle you could see through it) on my 3.0.  It was great for aggressive driving and pushing top speed in each gear significantly at the same shift points , but sucked for normal around town driving, cruising down the highway, and on the trail.  After speaking with a custom exhaust shop, the guy told me that I opened it up too much for normal driving, and said that I could try what the do on race cars, and that was reduce down the exhaust tip, or run a different muffler.  I didn't care for the drone of the muffler, so I swapped it out.