Salo, is a great film. I really wouldn't advise anyone watch it just for its shock value. While that is indeed its claim to fame and how it has remained relevant within popular discourse, the film is first and foremost a scathing attack on Italian institutional and political corruption. I think seen in this light, especially if anyone knows anything about Italian Fascism, post war reconstruction and the so called "Years of Lead," the film becomes a lot more powerful and indeed disturbing (just not in the gut wrenching way); not just a succession of somewhat shocking images that drunk teens can laugh at. But of course, this isn't how most people have seen it and I can only see those who go into it looking to be shocked, having those expectations met at least partly, but for the most part being disappointed because as I have said it is a whole lot more than that which I presume isn't the sort of film most people are looking for when they seek out "sick shit". It's a film I would definitely recommend, it is disturbing, it does make you feel dirty, just don't expect a run of the mill horror film.
In comparison to something like A Serbian Film, Salo really isn't shocking to be perfectly honest. OP, if you want to be disturbed try to find an uncut copy of that.
I hear the August Underground films are incredibly raw, I have little interest in seeing them tho.