I don't know about the second question, but I believe that all of the PDI cylinders make the bolt pull lighter and can increase fps somewhat from their slickness. Honestly, they aren't really needed, I know fuzzy didn't have an upgraded cylinder, but they are pretty sweet to have when sitting in prone position which a fairly heavy spring. I think I am going to buy the raven set, unless you think the others are far better. Not to steal your thread, but does anyone know the difference between the VC and HD series of PDI stuff?