One of the biggest issues with the transmission in your 2011-2019 GM Duramax is low mainline pressure created by the transmissions oil pump. Mainline pressure is directed by the valve body to the apply pistons and creates clamping force on the clutch packs, allowing the clutch packs to clamp quickly and completely. Reduced mainline pressure, or not having enough mainline pressure at the right time means reduced clamping force and there won't be enough to hold the torque of the engine. When clutch packs slip they generate excessive heat which destroys the clutch pack material.
The stock EPC functions to modulate line pressure. During a shift, the transmission control module commands the EPC to vary mainline pressure. The pressure will rise from 80psi up to 230psi. After the shift, the pressure drops back down to 80psi. At 80psi the clutch packs don't hold the torque of the engine. Towing heavy loads or adding aftermarket upgrades adds even more stress on the clutch packs.
The EPC blocker kit quickly installs between the EPC solenoid and the valve body. There is no need to remove the valve body. Just drain the transmission fluid and remove the oil pan and install the EPC blocker. Once installed, the EPC blocker will allow all the available mainline pressure, up to 230psi, to reach the apply pistons and clutch packs at all times.