8km atmosphere

[Pistitom]

Hi, I recently read a post ( terribly sorry but I forgot name and location ) about changing the visibility range ( I GUESS it was in SH4 - someone changed the 8km to 9...???)...I just wanted to ask if anyone knew which file to change in order to get a visibility of 6-7 km...Scene.dat ? Which values ? I get an fps drop when on bridge-100% the 8km range causes it...I don't spend too much time on bridge, so I guess my watchmen can do their job regardless of this minor change...thank You
ps: by 'visibility' I mean my own 'eyes'' range...I hope I wasn't too vague...