The stock D-Jet fuel injectors already are quite large
relative to almost any other injector that isn't for a
specializied racing application. Even then, people tend
to go to extra banks of injectors not larger injectors
since larger injectors aren't good at correctly metering
lower fuel volumes. I think the injectors flow at a
maximum of 37.3lbs/hr at a fuel pressure of 43PSI. More
than that and you risk getting them stuck in an overload
condition which I think locks them into 50% of maximum
flow (ie instant hole in pistons). Unless your motor is
making more than 250hp, it is unlikely that you need more
fuel flow.

A good solution in your case would be to add another
bank of injectors (or even just 1 or 2 ahead of the
runners) that only come on when you are at low manifold
pressure and at RPMs greater than 4000.

SDSefi sells kits for controlling extra fuel injectors.
They also list reasons why you want more injectors instead
of rising rate pressure regulators or bigger injectors.
They also don't seem like they care one way or the other
if you buy their stuff, only that you are happy with what
you decide to do.

good luck.
chris