What should i set my gain to with stock alt

[stfuFred45 0]

I have two sundown Sa-12s on a saz-1500d v.3 and a stock alt and battery. I'm probably in my car for an hour a day and i don't always have it turned up. Someone told me i can wire it at 1 ohm but to set the gain down. I have the big three so would this even be safe and if so what would i set the gain too?

[frogcase2002 393]

There is not going to be a place someone can tell you to put it. Just Set it before there is any distortion and watch your volts