As a general rule, Fimco has installed the proper size nozzles that correspond to the pump size. I am not saying you can't change the nozzles sizes to a little different size for your application. But try the factory nozzles first.
Pump rating are not what most people think. The Fimco Boom sprayer pump is rated at 60 PSI and 2 GPM. Pressure and Flow are a Inverse of each other. The Pump is rated at FREE FLOW for 2 GPM not 60 PSI @ 2 GPM. The more Flow (larger Nozzles) the less PSI. BTW the same model pumps can have slightly different out puts
The important thing about 12V demand pumps is PROPER NOZZLE SIZING. If the Nozzles are too small the Pump cycles and wears out quicker plus each time it cycles the pressure changes. (Cycles= Turning off and On) The best Set up is when the Pump runs constant and puts out a stead PSI & GPM for consistent calibration. This means having the proper Nozzle size.
Follow Wrooster's directions to both Calibrate the boom sprayer at a CONSTANT SPEED and adjust the spray nozzles at the same time for even distribution of product. Watch as the spray dries on the cement surface for that even application.
I have a Used 150 Gallon Boom sprayer that was one time used on a Golf Course. It would cost over $ 25 K brand new today. I still have to check Calibration and Distribution every so often on it. While Boom sprays can save a huge amount of application time, they are not trouble free.
it is one thing to do a off label applications. It is total stupidity to post it on the world wide web and expect people to approve.
You can lead a Donkey to water but you can't make the Jackass Drink