This is our forums in the nutshell. It's not that easy to tamper with discussions numbers. I don't see what cainer would gain from tampering numbers, it's not worth the time it takes to tamper with it.
As far as I can tell, it's not possible to alter the number directly. It is recalculated every hour and then stored *somewhere* but I have no idea where (I looked for it, but couldn't find it anywhere)