I had an experience with a '00 SS camaro that had more knock than a mofo, ended being a bad pcm or the latest calibration fixed it, we replaced his pcm with the updated flash and no knock at all.
Next guess would have been the knock sensors. Have you removed them before?

His car had knock thru every gear, and i recorded up to 12 degrees of KR. After the fix, i was able to add some timing and now his car runs great.

Your ltrims are ok, don't try to redo what GM spend millions on, keep it simple. As long as the ltrims are - you're fine. However, go ahead and try to get them exact, then check it the next day, lol, they are wrong again, hahahahah.

Every hand held tuner , other programmers' pcms i've looked at and recorded all shot + ltrims. It's not good or bad, just you end up chasing a/f ratio a little bit.


later,

allen