It's 4000 as HammerTech stated. (Hint: I believe he works for Hammer)
To answer your other question, if I remember correctly, it was brought up from 500 to 4000, i.e. 500 then 1000 then 2000 then 4000.
However, that being said, I found mine to work best at 2000. Put it at what will work best for you.