Stock springs have 78-82lbs of pressure seat pressure on average at 1.380″. If you are over 50psi (boost or drive presure) and 3,800 rpm, stock springs do not fully control the valvetrain. This allows a few negative things to happen. First, valve float, which can cause serious damage to the valvetrain. Second, intake and exhaust valves can be blown open by boost and exhaust drive pressure which allows reversion. Reversion can hurt your power potential by allowing exhaust gasses to enter the cylinder on the intake stroke. Inert gasses in the exhaust, when re-introduced into the cylinder shield the fuel particles from oxygen in the cylinder.
This does a few things that negatively affect power. It increases the time delay from start of injection to start of combustion, it decreases the maximum pressure and maximum temperature reached in the cylinder and it increases the total time needed to completely burn the available fuel. Correct valve spring pressure is a very important piece of power production. If you are running a tuner on an otherwise stock truck with a VGT charger, based on exhaust drive pressure, you need these.
We suggest them if you are over 50lbs. of boost(or drive pressure) or over 3800 rpm or when running aftermarket camshafts. We recently slightly lowered the pressure on our springs from 110# to 103#. If you are running over 4,500 rpm with a large cam, we suggest going with our 103# springs with different processing for better longevity in extreme applications as well as our light-weight 4130 or titanium retainers.