One of the main concerns this thread is about is that the larger you go on the nozzle atomization suffers. How badly it suffers is dependent on many variables. Until someone tests several different styles and sizes of injectors an captures the spray with a high speed camera it will all be speculation and theory.
I tired really hard to stay out of this thread... but... here I am.
I am sorry but you don't need a high speed camera and it is not speculation, it is simple science. I am not trying to come off as a jerk, but here is why...
Given any RPM, Inj PW, and nozzle size and keep it constant... As icp goes down, your atomization goes down. As ICP goes up, your atomization goes up. Very simple principle that everyone can agree on.
Keeping nozzle size, rpm, and INJ PW constant. As ICP goes up, you will dump more fuel. As ICP goes down you dump less fuel.
Keeping the nozzle size constant. If you want to dump the same amount of fuel. Then as your ICP goes up, you must drop your PW.
Now keep the Inj PW and ICP the same. As nozzle size goes up you dump more fuel, as nozzle size goes down you dump less fuel.
So to dump the same amount of fuel given a larger nozzle, you must drop either Inj PW, ICP, or both.
Simple so far... right? All concepts we can agree on. So why does this matter?
At a certain point the nozzle size gets so big that you must drop ICP and Inj PW enough that it causes two negative factors. As you drop ICP you will lose atomization. Also at a certain point when you drop Inj PW at lower rpms you will miss the optimum window in which to dump fuel and optimize torque. That is why it is so hard to get bigger nozzles to run right down low.
This has been tested by many people on the dyno and has shown that smaller nozzles produce more tq down low, bigger nozzle produce more HP up top. This is basically just a different variation of what Jay said in the first post.
In short, less ICP means lower atomizaion. Keeping everything else constant, smaller nozzles can run higher ICP when compared to a bigger nozzle.
Also... too short of Inj PW will just result in a lot of noise, you need to be fueling on the way back down. Not just at TDC. There is an "optimum" window to dump your fuel to maximize power efficiently.
Using the same science... smaller nozzles will struggle on the top end because the PW becomes too long and now you are missing the "optimum" window to dump all the fuel.
People can argue all they want. And talk about how great their truck runs, I don't doubt it runs great, but there are pluses and minus to nozzle size. No perfect option. Anyone that takes the time to test these theories on a dyno will come to the same conclusion as everyone else that has tried.
Once again... my dyno is open to anyone that is willing to put in the time to test these theories.