Higher VOP pressure is due to stiffer springs. The effect is pressure will build higher before the spring in overcome and allows injection. Higher VOP will typically show a clean burn out the pipe due to increaed atomization however it reduces overall hp. Also without tuning changes increasing VOP retards timing and shortens overall injection time without increasing commanded PW as it takes longer to crack open.
The B codes that are used in the DT466 and 530e engines use 5 or 6 hole nozzles that have holes much larger than a stock 7.3 nozzle. This is probably why the VOP was set to 3700 to increase atomization on a larger nozzle. My B codes with 200% 7 hole nozzles are pretty clean at low load and idle even when cold without a chip and idle like a stock truck. I want to say the holes on a stock B code nozzle were equal to that of a 200% nozzle.
Again higher VOP increases atomization however reduces overall power and without tuning adjustments the nozzle has more delay and will inject less time as commanded due to the delay. At the same time modifications to flow inside the injector could probably overcome of those issues.
The B codes vary in sizes. BA, BB, BC are basically a stage 1 AC code injector with 3700 VOP springs and different nozzle. BD is the 240cc single shot. BE is an AD with higher VOP and different nozzles. BI, BG, BJ, BH, BN are all the same larger split shot injectors with different nozzles. They can flow 275cc but need 6ms to do so (split shots always need more time to inject) All B codes are 3700 VOP and all A codes are 2650 VOP.