When running down the highway the truck will start to surge when staying at 65 to 70 but not when accelerating could the pump be going?

 

I realize it's not apples to apples with the difference between 12V and 24V, but with your mods and a "bigger turbo", thats right in the rpm range where the turbo wants to start spooling and the speed wont allow it. Mine will do the same thing with my Adrenaline on higher settings. Just a guess.