How do I know when to stop adding timing... when I get knock, or is there an optimum amount with diminishing returns after that point

I am doing all my testing in 4th gear to really LOAD the engine and induce KR if it was going to happen....

I am currently running 28-29 degrees at WOT from 5200rpm and up..... NO KR yet. My mods are in my sig, heads combustion chambers are 66ish CCs

 

I was running 30-31 with no knock, but power dropped off. It runs stronger down around 28. I haven't tuned/tested to find the ideal setting yet.

 

add more octane with 30-31 (toluene?) and see whaddup.

 

When you reach your maximum power output.