Stock springs have 78-82 lbs of seat pressure on average at 1.380". If you are over 50psi boost or drive pressure, and 3,800 rpm, stock springs will not properly control the valvetrain. This can cause valve float, which will affect performance and can damage the valvetrain. Another thing that can happen is intake and exhaust valves being blown open by the exhaust gasses, and letting them back into the cylinder during an intake stroke. 

Correct valve spring pressure is a very important piece of power production, and unfortunately is often overlooked. If you are running a tuner on an otherwise stock truck, you will need these springs.

We recommend them if you are over 50 lbs of boost pressure or over 3800 rpm when running aftermarket camshafts.