I just shot mine across the chrony this morning and will post the actual data on a separate forum string but here is the crux of the data you were looking for.
Gun: FX Streamline .25 no mods shooting on hi pwr; fill pressure 230Bar. Zeroed at 30yds using standard JSB 25.39gr pellets.
JSB KING HVY MKII (33.95gr)
shot string: 10 shots
avg: 831.9 fps
ES: 11.88
Sd: 3.60
Average Energy at the muzzle: 52.18 ft-lbs.
POI drop is approx 1/2" at 30yds
(For comparison the standard kings 25.39gr have avg. 945fps velocity; average Energy at the muzzle: 50.4ft-lbs.)
For the fun of it, I also shot on medium power, just a couple of shots
620.7fps
POI dropped approx 2.25" at 30yds
For the fun of it, I also shot on Low power
441.8 fps
POI dropped approx 7.0" at 30yds.
You mentioned that you want to use the gun for bird pesting out to 100yds. You didn't ask for it but here is an opinion on what pellet I would choose. The JSB heavy (33.95gr) only carries approx 2ft-lbs additional energy at the muzzle. As you can see by the Point of impact (POI) info I included it will have a much more parabolic flight path at longer distances, than say the JSB 25.39gr. From my observations I would choose the 25.39gr over the 33.95gr for practically any type of pest bird application, and here is why. When I'm pesting, my ranges change with almost every shot, I would prefer a pellet path that would be as flat as possible so that a shot at say 50yds would only change POI of about 0.5" at 75yds, rather than a heavier pellet that will have to be compensated (probably by holdover) that might be several inches difference between 50yds and 75yds. In all honesty, I have not found the heavies to be any more accurate than the 25.39gr pellets out of any of my guns shooting out to 75yds. I'm not knocking the heavies, but I just don't have an application where I need to use them that the 25.39gr don't fill the bill better. Now with that said, I could see if you were shooting bench style of shooting at known distances and wanted something to buck the winds a "little" better maybe. Then that would make some sense to me. Please don't take offense to my diatribe, but I just wanted to share an opinion that might be different than the direction your thinking, so just take it with a grain of salt and if it helps, great and if it don't then it's just another opinion. Wishing you the best of luck with your Streamline, I know mine is one of my favorite guns.