1) fast changer
2) faster field stripping
3) fiber optic sights (if you use them)
4) 2 inch longer barrel (doesnt make much of a difference, but oh well)
5) faster loader (maybe)
6) VELOCITY ADJUSTER!!!!
When I got my PGP2 it looked awesome. When I played with it it did awesome. The top loader fell off one time, and it broke, so now I just take off the loader to reload it.
The velocity adjuster pretty much just stays at 250 fps, because any higher and the ball will break, unless you have a venturi bolt, polished barrel, and a right paint to barrel match (small).
I got this thing for 90 bucks, and it was worth it. Sometimes I play with the PGP2 at my field, just to have fun with the walk-ons. It is a very fun gun to play with.