Pushing up to 177 kPa with the VSR78/75. Takes a couple SECONDS to build thrust- Muffler is probably slowing down the spool.
Still using STOCK gm truck fuel pump, AFR10.5 up to 4000 rpm.
Injectors at 60% duty cycle. Likely at the end of Fuel pump volume. Close to wastegate spring pressure- 12# spring combo installed.
Still pushing through STOCK muffler, 2.5" pipe is definoite bottleneck. Thinking about Y pipe to a boost actuated cutout and a 3Inch chinese "Resonator".
. I think the AEM 340lph Fuel Pump needs to get installed first, before I melt any expensive parts.

 

................... Don't know what happened to OP, must have been a typical " Drive-By" ...

Opened up exhaust to 3.5" all the way over axle to back bumper, used a Walker diesel bus muffler, nice LOW tone, zero drone.
AEM 340 LPH pump: static fuel pressure 58psi, pops up real quick a hair over 71 PSI.
Boost now builds VERY DAMN QUICK. consistent 193kPa with 12# wastegate springs.

VSR7875 Gen 2.5 .96A/R is certified "Perfect Fit" on a 5.3 Liter LS in a 6000 pound 4WD.
.
. As far as SPOOL, Exhaust made ALL the difference, stock 2.75" GM muffler and pipe choked at 4400 rpm.
Here's the speeding ticket:
Walker # 21470 3.5" ID straight through:

 

Pics of setup?

 

Look at Huron Speed V4 assembly instructions ( down load ) about 12 pages of mostly pictures... My install looks just like Huron Speed instruction(s).
. Pretty easy, straightforward, mostly GM parts used, like IAT sensor, 2 Bar MAP, electric fans from 2006 models.
Really, everything looks pretty much like it WOULD if the factory had a Turbo option that year.