air/fuel ratio is dependent on octane rating, and out here in cali we only have 91, while other parts of the us get 93. With our crappy gas if you want to run high boost levels you have to run rich. eventually you reach a sweet spot where anythin richer is just too much fuel, but running as rich as 10.8 with as much boost as you can wil make more power, than for example, a little bit less boost on a leaner setting of 12.0. NA motors can naturally run way leaner because with less air going in, there is less likihood of knocking.

 

lol ya my car is lean my plugs look like candy canes... with out the red swirls. Its a factory leaning out process. With out a cayt the ecu reads the car running too rich and it gets leaned out..... but I have a little trick to keep the egt's low, instead of spraying meth or water... I am spraying oil via ringland cyl3. OH ya!