CW racing To do the math I had to provide some inputs that you did not supply IE fuel pressure I used 6.5 psig nitrous pressure , I used 900 psig and number of jets I assumed 4

A solenoid with orifice of 0.63 will flow the following under IDEAL conditions Fuel = GPM = 0.277 /CC/min= 1077.3 / lbs/sec=0.13 amd lbs /hr= 102.6 nitrous = lbs/sec=0.13 / lbs/min=7.8 /lbs /hr=476.5

so 4 x jets at 0.03 will flow fuel = GPM=0.251 CC/min =976.5 lbs /hr =93 nitrous = lbs /sec =0.12 lbs /min =7.1

4 x jets at 0.032 will flow fuel = GPM= 0.286 CC/min =1113 lbs /hr = 106 nitrous = lbs /sec = 0.13 lbs / min = 8

so 4x 0.03 jets theoretically will be served by a 0.63 solenoid but in real life I don't think it will due to the sum of all the losses and 4x 0.032 will not ,a solution is to use 2 solenoids in parellel or a solenoid with a larger orriface

Hawkwind