FX impact info

I just received my first Impact and its the .25 cal, 700 mm barrel M3. I wanted to get some opinions and info on power settings ect. I have 25.39 JSB, the 33.34 (i think), JSB knockout slugs, and the FX hybrid slugs. I have not shot it yet but Utah Airguns states it shoots the 25.39 at 950fps in testing. I will for sure tune that down to 900 mark. I'm mainly going to shoot the FX hybrid slug for hunting. Any easy setting advise would be great.