Rifle or pistol? Benjamin specs 700 fps as max for the pistol. AFAIK, the pistol is only available in .22 cal.
The YouTube videos are about the rifle.
And....this is the handgun forum.
Look up modified Marauder pistol on youtube- one guy has his shooting 650 FPS levels with the heavy 28 grain eugin pellets and 980 FPS levels with the lightest .22 pellets.
Increasing the Hammer spring tension, hammer throw length, and transfer port size are the main ways of power tuning your precharged PCP pistol.
You can attain up to 19.8 foot pounds with the marauder pistol...like i said though, you won't get too many consistent shot strings.
Oh and there are a few who own specialized .25 cal marauder pistols- go youtube it
p.s.: Very expensive conversion. I think the .25 cal conversion is getting close to 40 foot pounds!