Playing with just the fuel pressure is a pretty crappy way to tune something. You're basically trying to squeeze more fuel through the injectors than the ECU is telling them to dispense. It's imprecise and for bolt-on mods, the ECU will easily detect the difference and still deliver the right mixture. Your standard intake, header and exhaust combo is not going to cause the ECU to run lean. It has sensors to tell it there's more air entering the engine.

Now, if you drastically change the airflow characteristics of the motor (i.e. cams or other internal mods; or forced induction) then you've gotten yourself outside of the ECU's range of adjustability. Is the solution now to just increase the fuel pressure? No, for a couple reasons. One, the stock Honda pump flows less at higher pressure. Two, you haven't increased the capacity of the fuel injectors. To get more fuel into the motor the injector has to stay open for a longer amount of time. This amount of time is called "duty cycle" and the only way to change it is with some sort of electronic fuel controller like an A'PEXi V-AFC or Fields SFC VTEC. These controllers modify the signal the ECU sends to the injectors to change the duty cycle and thus change the amount of fuel going into the motor. This is a perfect solution for a car that's still normally aspirated, and works pretty decent with a forced induction car.

The problem with forced induction is that while the stock Honda MAP sensor is able to send a signal out that indicates there is positive manifold pressure (a.k.a. boost), the ECU is unable to interpret this signal. This would require more complexity and since a normally aspirated motor only operates within a certain range of manifold pressure, that is the range the ECU is able to work with. In more simple terms, boost makes the ECU throw a check-engine light, and to solve this problem you have to not allow the ECU to see boost. So if the ECU can't see the boost, then the add-on controller can't really tune based on boost. For a boosted car the best solution is to either have the ECU modified to read boost (Hondata does this) or replace the ECU with one that is able to read boost (AEM EMS). These are both fully programmable solutions that are capable of seeing the boost signal from the MAP sensor and know what to do in response to that signal.

Sorry for the essay, but specificity can be used to solve an argument over generalities. Damn I'm such an English Major.