ok, so that is to protect the engine from detonation under boost. Loads of fuel.....
With larger injectors and higher fuel pressure you will run richer than stock at idle. Not much the DME can do about it and here is why: An injector has a minimum pulse length on the order of about 1mS. That is the lowest flow rate. Below that the injector doesn't open and the engine stops. The minimum opening time X multiplied by injector flow rate is the amount of fuel the engine is getting. And the flow rate is directly proportional to the idle fuel pressure.
With your setup I would have expected slighly lower fuel pressure at idle compared to the stock regulator to compensate for the larger injectors. But your FP is higher. That doesn't make sense.
Ask Promotive about the specs.
Ingo