Alright back at my old computer.
With the standback stuff: It was logging over injector time but I couldn't change the start times, which is exactly what the ptp guy stated. Without the ability to phase the injectors you are stuck with the factory window. You can't "preload" the fuel charge.
One way around would be an auxiliary fuel system, as mentioned.
Another would be a wet nitrous kit, that'll get you power.
If the ecu maps can be cracked to allow injector phasing the power potential should go up quite a bit. I believe someone on that thread went over injector timing. Injector timing is expressed in milliseconds of pulsewidth, this tells you how long the injector is on. Your window of opportunity is very very small and gets smaller as rpm goes up. Some ecu's are setup as an end time and when you add signal it adds it to the front of the signal, some ecus are setup as a start time and it adds as you go. From what I read, if I read it correctly, the DI Mazda ecu has a preset start time and goes from there.
The problem is once you exceed your window of opportunity you are essentially spraying fuel out the exhaust valves and into the exhaust...doesn't work to well when you need combustion inside the cylinder to make power.
So a few alternatives were mentioned and promptly dealt with. Better flowing injectors would get more fuel in there, but not much compared to the headache at idle. Adding fuel pressure will get you more wiggle room as it also increases the size of the injectors, but you are still on the time constraint. The other option is to get it so you can phase the injector timing. This way you can "preload" the opening of the injectors so you can get the maximum amount of spray into the combustion chamber before the exhaust valves open (and before spark obviously).
OR...
You add a wet fuel setup. This could get tricky depending the intake manifold design, but it would be possible to add a "5th injector" (or 7th injector) and control that on a boost only way. The GM guys have been doing it for years with some success. I remember tuning a cyclone that had stock fueling, a massive turbo, and a large additional injector setup. Car idled stock and made 450awhp, not bad out of a truck on pump fuel (92 octane).
It looks like Cobb is trying to crack the phasing control. Many standalones have control of phasing control on regular efi setups, but direct injection is another ballgame because your window of opportunity isn't as large. You can't have fuel on the back on the intake valve waiting to go in (not a good idea but I've seen it done), as you will just be pooling fuel into the piston, again not good.
The more I think about it, I think the more I like the idea of developing an aux fuel system as roadragemotors mentioned (what is your name btw?)
