DV flutter
 

Sometimes when i let off the gas pedal slightly i can hear my diverter valve flutter instead of just a clean release. But other times it doesnt do it. Do i need a stronger or weaker spring or should I shim it or is this normal? Thanks in advance.

You have a single spring that is set for peak psi. When you are part throttle with less psi, its going to be stiff. This is normal and why HKS makes a ssqv and other companies make dual stage valves.

good to know. thanks cincy