Here is Cobbs recommendations on what constitutes bad knock.
General Guidelines for Monitoring Knock on a Subaru – COBB Support
For me as long as i dont see any knock above 2.0g/rev and it doenst pull more than about 2 Deg of timing then its fine. You mostly just have to be worried about WOT. The knock sensors on the EJ or set so sensitive no matter how perfect the tune is you are going to see something occasionally. Ill usually see a couple of hits on my 30ish min commute to work.
My mods since you asked are pretty much full bolt on+ Dom 1.5 & E85.