If you unscrew the reg from your body, then the top of the reg should have a center hole and several smaller holes around the perimeter. If you have ring pliers, you can put the points of the ring pliers in the perimeter holes and then unscrew the reg from the body. If you don't have ring pliers, some skinny needle nose pliers also work.
The technical info regarding the updated parts performance will have to be answered by Eric, but from a laymen's words, it makes an awesome marker more awesomer!
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I have LEGO Paintballer Mini Figs