It all depends on the strength of your HPOP. Factory tolerances are kinda loose, so some HPOP's can keep up better than others. Most HPOP's can't even keep up with stock injectors on a higher hp tune, so the chances of the stock HPOP keeping up with aftermarket splits is virtually nil.
However, after the discussion in this thread, it looks now like you are leaning towards singles. Wise decision IMO.
Singles use less oil than splits. For example, you can run a chip on stock injectors and a stock HPOP, and in a higher hp tune you can see injection pressure drop to 2000-2200 psi. Simply swapping out to hybrids (a single shot injector), and you can easily reach over 400 hp, and at the same time see injection pressures hold 2500+ psi in many cases.
The only true way of knowing for sure is to monitor injection pressures after you install your new injectors. If the HPOP is still dropping pressure, and everything else has been verified to be in good shape, then you might have a weak HPOP and require an upgrade. Fortunately, there are now many upgrade options on the market today that fit just about any budget.