I’d disagree based on my personal experience years ago. Now mind you this was a mostly stock truck. Had an exhaust, intake, gauges and reputable tuner but had stock fuel, stock oil, 4.10 gears, 31.5” tall stock tires, and Auto trans.
At the time I lived in central Montana and nearly always had a loaded trailer behind me. Minimum weight being pulled was 7k but usually up to 15k. The STOCK turbo with .84 housing “choked” the truck out when you got north of 2200 rpm. I would normally run down the highway at 2500 to 2800. It was all I could do to get it up to where I needed to and typically when I did it surged horribly! My only change was installing a van turbo (1.15 exhaust housing). The way I drove it at slower speeds in the lower rpm range, I noticed NO change to spool up and no lag. What I did notice was “my” upper rpm range was drastically different. Truck didn’t level or or choke out anymore. I could get to, be in, and maintain with lower egt’s without surge. I could get to and drive comfortably in that 2500 to 2800 rpm range where I couldn’t before.
Again, my only personal experience with changing exhaust housings on essentially the same turbo. But for my truck, my style of driving, and my location at the time, the larger housing was a benefit in every way. I know that other people did not have the same experience that I had.
With my newly acquired 7.3 that is basically setup exactly how the truck I described above was suspension wise, I have no plans to run bigger tires or do a gear swap to 3.73. I will be pulling similar weights and the same speeds I was before. My elevation now will be a few thousand feet closer to sea level than before though! If I decide to swap out the 38r that’s on it now, I’d like to go to a 364.5/73. The exhaust housing is what I haven’t decided on. Most testing and most people in general are running different gears and larger tires than I will. And I know first hand that the exact same engine trans setup performs differently when gears and tires are different.
Take the 6.4s I had for example: my 08 with stock tires and 4.10 and my dad’s 10 with 3.55 and 35’s. I built both engines and they were identical. Mine ran 20 mph slower at the same rpm as compared to my Dad’s. His was sluggish at lower rpm where mine was responsive. Mine was a towing machine at 65 to 70 mph, his was a dog at that speed due to lower rpm. His had much longer legs on the top end than mine did and running empty his got better fuel economy and was much nicer to drive at interstate speeds.
I know it’s all relative and if I decide to swap turbos, changing the exhaust housing isn’t terrible hard with the t4. Just hard to figure how something may work for me when many of the 1st hand experiences don’t run a setup like I do. My big tire days are over! Lol