I can get about 700 fps after installing flat top piston/valve in my Crosman Drifter

Phase 2 of my Super Drifter project. In Phase 1 I added a longer barrel to my Crosman 1322 American Classic to make it the start of a Super Drifter. In this video I add a custom piston/valve kit and several other parts to increase the speed more than 150 fps, and it can go higher