Any idea what that little can is?

I have forged pistons, how concerned should I be about knock with a s16g turbo on say 20 lbs of boost w/o knock sense? My intuition is that any knock at that point is probably bad.

Does anyone know what safe timing and AFR numbers are for those levels of boost? Any things I can research?

I can run 93 octane, but I am considering using table switch/boost control to have a ~91 octane setup to save some money during low performance commutes.