Ported Valve VS. Non Ported Valve 1377

[Bad Moon]

What's the difference ? And are there any Pros and Cons to either?

[1377x]

ported less restricted
non ported less efficient.
i just flat topped another valve in a 1377 this one i didnt port using basically all the same parts of the gun excluding the valve
its about 50fps shy of my ported ,a huge port,more modified valve at 10 pumps