Add fuel above 12.5 k and slowly ramp down timing to stock values at 14k. Running an engine at high rpm max load puts a lot of heat in the cylinder. Add fuel to cool it down. I have added fuel in the past to get through some knock due to timing, but at high rpm and high load I would just pull the timing. You are not there long enough during normal use to lose too much power.
My .02 worth
My .02 worth