Unless your problem is insufficient pressure, which I doubt, it alone will probably not increase braking peformance (ability to achieve optimum baking from the system and reduction in total braking distances and fade).
Now maybe with very large tires you may need increased pressure, but that is still probably not enough to improve perf. Think of it this way, does stepping on the pedal harder improve performance (see above definitions). Not necessarily. The cause of poor performance is not pressure alone, it is poor mechanics in the caliper, swept area, rotor quality, and inability to modulate said pressure to achieve optimum braking (15% insipient skid).
Lets say that every time you touch the pedal you get instantaneous full pressure at an amount double your present psi. Would that increase the perf? No. You would get uncontrollable, full wheel lock. Assuming you have sufficient pressure to lock the wheels (see above comment on very large tires), you must them be concerned with mechanical efficiency and ability to modulate the pressure. I am avoiding brake fade for now, another system efficiency issue. If you are not capable of generating sufficient pressure to achieve wheel lock, then a achange in booster/mc is only one part of improving total system performance.
Then we can discuss man/machine interface issues. Studys (mostly MB) show that in general people do not achieve sufficient pedal input to get full braking when needed (even when forwarned), thus we are seeing systems (again mostly MB) that increase pressure themselves when it is determined that the driver needs heavy braking, called something like "panic" braking. A new booster/mc may assist in achieving faster, heavier braking, but again, that is mostly an interface issue. The wheel brakes cannot perform better than they are capable of, ultimately (assuming you can get there already). But you may be able to extract better total performance by better pressure modulation.
The factory calipers are poor mechanical devices. The dumb blade that is supposed to slide smoothly cannot due to the flexing of the frame and subsequent "divots", which then serve to bind the smooth operation of the caliper. A single piston caliper makes it difficult to have even pressure along the length of the brake pad, which can cause binding, poor/incomplete friction over the swept area, and pressure spikes. Generally, the more pistons, the smoother and more even the pad pressure distribution.
Uh, thats probably enough to digest for now.