This also goes hand in hand with the physycal limitations of direct injection. For a maximum power maximum tunability standpoint it just dosent make much sense.
It all has to do with the way the system works and how fuel can only be introduced at a specific window in the combustion cycle.
The problem with DI is that injectors cannot fire out of phase. As the RPM goes up the MORE fuel the engine will require and the LESS time the DI will have to inject it.
In port injection you can pretty much have the injectors dump fuel 100 percent of the time regardless of the engine phase. The valves control the fuel/air delivery
Meaning you can NEVER run the DI injectors to 100 percent IDC. They can only run at the IDC that is in phase with the engine rotation.
In direct injection all the fuel must be injected in the last part of the intake stroke and the beginning part of the compression stroke. As RPM’s rise the fueling window becomes less because the strokes becomes faster and as a result there is less time to inject fuel.
Essentially with DI the more power at RPM you make, the RATE fuel delivery needs to increase EXPOTENTALLY because of the decreasing time the injectors have to fire in the correct phase. As we know the square of anything becomes real big real fast.
The overall fuel delivered between port and direct injection does not change BUT direct injection must deliver an enormous amount at one time to match the engine phase.
For this reason Formula 1 cars that use RPM to make power still use port injection. The fuel requrements at RPM would make direct injection an impossibility.
Direct injection is most optimally used in diesel engines because of the lower RPM’s that diesel engines produce as well as the energy density in diesel fuel.
Unless we are willing to spend boatloads on super high flow gasoline DI high pressure injectors that dont even exist yet. I think it would be best to convert the car to port injection for high power needs.