Progressive rumble tune

Hi all need some help raping my head around this. My friends truck has a tune in where when its cold at idle acts like a normal duramax with the restricted turbo 85% on vein position. But as it warms up it restricts less and less and at operating temp sounds like it is pretty much at 0% vein position. Im trying to figure out how you do this in tuning. Obviously the rumble tune is just setting the veins to around 20% at idle but if you do that than it pretty much is always like that regardless of temp. Im trying to figure out how they got it to change with ect. Of course both the ecm and tcm are locked on the truck so I can't see what they did. I just really like what they did with making it progressive, that seems like it would help with warm up and just seems more factory. Any ideas?