I have done several AFR tests on a LOAD based Dynapack and my conclusion was when running PUMP Fuel (RON98 ~ MON93) that best Power was around 11 - 11.5 AFRs. I tried leaning out as lean as 12.2 and got no extra power but more knock activity. I tried richening up in the hope to be able to add more timing and gain more power but that didn't work out. I went as rich as 10.4 AFR and instantly lost 40 BHP. There was no way timing was going to recover that.
On a TMIC I would use 10.8 ~ 11.2 AFRs thereabouts.
On a FMIC I would use 11.2 ~ 11.5 AFRs thereabouts.
There is typically much more Torque/Power to be had from properly dialling in AVCS on a LOAD based dyno than playing with AFRs.
My 2 cents,