Larger nozzles- By installing larger nozzles you are makeing the nozzles less restrictive so that more fuel will flow out of them with everything else being the same. Stock injectors with stock programming and larger nozzles will get more fuel out and make more power. Stock injectors only modified to have more fuel capacity with stock nozzles and stock programing will run exactly like stock injectors. In this case the only way to get more fuel out is with a chip to extend the open time of the injector and/or increase the Injection Control Pressure (ICP) to push more fuel out the nozzle. On the same note if you say make a hybrid (installing a larger 7mm plunger and barrel out of a DT466/I530E injector) and leaving the intensifier piston the same will effectively reduce your injection pressure. This less injection pressure will make less pressure at the nozzle and will actually flow less fuel with a stock nozzle than a bone stock injector. So to get the fuel out without a chip you would need larger nozzles.
There is also a point where the stock nozzle just wont flow enough fuel to get the desired amount out in a realisitic time frame. That's why high capacity injectors require larger nozzles to use that capacity.
Codes- All powerstroke and T444Es come with A code injectors. A code injectors have a 6.0mm plunger and a 16mm intensifier piston. What this does is multiply the ICP so that injection pressure is adiquate but not having to have huge amounts of ICP like say in the 20,000 psi range. This difference give you approximately a 7:1 difference and therefore increases your injection pressure 7 psi for every 1 psi of ICP.
All DT466s and I530E injectors are B codes. Of those some DT466s and all I530Es have a 7.1mm plunger, hense more fuel per mm of stroke, with a 17.5mm intensifier piston. This gives you approximately a 6:1 ratio. So no it will not have quite as high of ICP as as the A codes but it's not as bad as it could be. However due to the larger intensifier piston they reqire much more high pressure oil to make the piston stroke the same distance. This is why you need a high pressure oil system with a higher capacity.
Hybrid injectors are taking the 7.1mm plunger and barrel out of a BD code I530E injector and installing it into an A code injector with a 16mm intensifier piston. As you could imagine the down fall is that the injection ratio is dropped to approximatly 5:1 further decreasing injection pressure. However with the smaller intensifier piston it requires no more oil than an equivilant A code yet it flows the same amount of fuel as a B code. The result is much more fuel capacity without the need for more high pressure oil volume.
A codes and B codes can be further broken down as well.
A and AA injectors came in the '94-'97 non-california trucks. They are all 90cc injectors and are single shots.
AB injectors came in the '97 cali, and all early '99 trucks. They are split shot injectors meaning they fire a small pilot shot before the main shot. These injectors flow 130-135cc of fuel.
AC injectors are found in the high torque version of the T444E and do not come in any Powerstrokes. They have the same internals as the AB injectors with the exception of the single shot plunger and barrel. However due to them being single shot injectors they flow 160cc. This is due to the way the split shots work. They have a small passage that opens, much like a port in a two stroke engine, that are uncovered that bypass the injection pressure out the side of the barrel instead of out the end through the nozzle. Because of this pause a portion of the travel of the plunger does nothing for injecting fuel so a split shot injects less fuel for the same amount of travel as a single shot.
AD injectors are also split shot but flow 135-140cc of fuel due to a slightly longer plunger stroke. These are found in all late '99-'03 Powerstrokes and T444Es.
AE and AF injectors are essentially the same as AD injectors but were called a long lead injector that was used as an attempt to cure a "cackle" issue many people complained about.
BA, BB, and BC injectors are essentiall all the same and are the same as AC injectors but are found in some DT466s.
BD injectors are the only B codes with the larger 7.1mm plunger and barrel that are single shot injectors. These are the injectors people are usually talking about when they are talking about putting I530E injectors in their Powerstrokes.
BE injectors are essentially the same as the AD injectors but found in some '97-'99 DT466s.
EF, BG, BI, BJ, BN and BP injectors all have basicly the same capacity and are split shots. However the nozzles vary on them depending on application. They can be found in many DT466s and I530Es.