I'll turn the pressure down 2psi and see what happens. If the 8.5:1 ratios "go away" then maybe I will turn the boost up a psi or two and see what the A/F and O2's look like.
I don't think those ratios will go away with fuel pressure adjustments. It may change the actual amount of fuel being delivered (assuming your BLM stays the same), but the ecm doesn't know that. For the same set of conditions, it should calculate the same injector pw, no matter what the fuel pressure is. That's the reasoning behind using a BLM lock, to make sure that the injector pw comes up the same each time, so that changing the fuel pressure does in fact change the amount of fuel delivered.
I am confused by your statement that the A/F ratio displayed by DS is being "commanded" by the ECM. Why would the ECM be calling for more fuel when the O2 signal is already really rich?
At WOT the ecm is not looking at the O2 sensor any more, it doesn't know that it is rich. It knows the rpm, the MAF, coolant and air temperatures, TPS position, the BLM, stuff like that. From those inputs it calculates the amount of fuel to be injected and tries to inject that. It doesn't look at any feed back to see if it is rich or lean. The chip programmer can change some of the tables around in the chip to get it to inject more or less fuel for a given set of conditions. It just sounded to me like yours has been programmed for more...
John