.25 B/P Main Valve Setting

What is the best setting for the main valve VST on a .25 B/P that is already reg tuned at 900 fps, one or 1+1/4 turns CW after contact? My .22 Std. preferred only one. The .25s require more volume so I’m guess it would be less than a .22 setting?, but the reg is set slightly higher than a .22