Lowest is basically 0 as you can close the valve all the way. Highest FPS it will depend on the setup, gas used and weather. With stock setup I was able to reach almost 2J using 0.36g with 150psi gas at around 30°C. Sorry for the late reply, I was off the channel for some time. I intend to post new content as well as a new improved installation guide and some testings and comparison between FEDA, Ratech and Revanchist valves.