1. Do you have an adjustable fuel pressure regulator? Lowering fp should lower O2s.
2. What scan tool are you using to look at the O2s? Some, likke the OTc4000 read .500 when the key is turned to the "run" position and others, like Direct Scan, TurboLink, or ScanMaster read .441 in the "run" position. (engine not running)
If you are using one of the latter three, something around .800-.820 is probably pretty good for 93 octane. If you are using OTC, AutoXray, etc, then .860-.900 would be more the range. Now, depending upon what chip you are using, knock at 15# may, or may not be normal. Most of the modern chips seem to be able to run 16-17 on 93 octane.
And, of course, it has to be real detonation and not false caused by a bad motor mount or down pipe hitting the control arm, etc.
I am over in the sw side of town, Chimney Rock, South Braeswood area...I will be happy to help you with it if you wanta come by.