You can also put a rood in place of the wg actuator to keep the wg open and use a throttle cable stop between the tb and the end of the cable outer cover to tune without boost on several part throttle points, this will give you several part throttle curves that are repeatable, then you can do increasing boost runs.
I am not an expert, only tuned a few times and there maybe a way to do this that i dont know about, but it was actually easier to do this than to try to hold an exact kpa while the dyno makes adjustments to its braking to hold speed while i play with timing, look at torque and all at the same time.