From ZZP's website: ZZ Performance
They will work fine with stock springs and pushrods. The only thing I would worry about is if you are running stock springs, and they are high mileage, you might want to replace them so you don't break one.These work with all stock or aftermarket pushrods, lifters, springs, retainers.
As for noticing a difference, yes, you will.
Higher Ratio Rocker Arms