I have just got hold of an Impact Mk II power plenum in .25 with 700mm barrel.
With the hybrids I zeroed at 30 yds I have shot them to 60 yds so far with good results, which suggests that they will be fine at 100yds, haven't been able to shoot at this longer range yet.
Reg pressure 100 bar, max power wheel, valve stop at 4 rings, haven't adjusted the hammer tension yet, chrono at 930 FPS
I will be going up to 980 FPS in a few days by incrementing the reg, maybe a bit more hammer spring tension and then when I get the speed I will slowly turn in the valve stop until the speed begins to tail off - hope this helps