What exactly is your question?
If you buy a dual stage plate then you can run two stages independently of each other. The 25 shot can be dry if you want just add a little fuel if needed through your injector(tune). If your A/F is currently say 11.8-12.2 then a 25 shot should not need any extra fuel. But if you are at 12.8-13.0 A/F then you may need to add some fuel.
Some nitrous people run A/F in the 12.8 range even on 100 shot or more with no issues.
