You can but saying it like that is more a reference to people than things. You could say: "Who knows this mod exsists?" That would be better. I don't really care how you say it...I don't think anyone else really does either...they just like to tease.
I voted no because well....I never heard of any mod like this until just now.
Well, I, personaly, are disturbed by repeated bad english.
And of course you can type whatever you wish, but don't think people will take you seriously if you do.
Who knows about this mod, or Who knows this mod exists, would probably be the best names.
Who is familiar with this mod, would also work...