Both of these things are intentionally capped by script. Adjusting them without knowing how the code works can cause undesired behavior.
I am still on the fence with how I will arrange things in the coming updates to the mod. Specifically, I can't have more BCSO cars until I make all the bases needed for them, which could take however long. I don't want to include repeats of existing vehicles, for sake of pumping the numbers up.
Regarding volunteer firefighters, the reason I asked for people's real life POV's was a fun way of adding more volunteer personnel to the mod so that more personnel can be playable.
Thank you for doing the research on this one. I have evidence now and I can make that judgement call with the mod. I'll have it be courtesy lights by default (as it is now) and sort out the lights/sirens commands later on.
I still don't know how I'll proceed with that because Dillon's batt chief appears to also be a POV, while Lima VFD has a dedicated vehicle. Maybe I'll keep their speed the same but remove the sirens from the 2 chief vehicles.