[Geo]

I thought Optima batteries didnt vent cause they were special type or something.

No, you need to vent an Optima. It is a gell cell. You don't need to vent a WestCo since it's a dry cell battery.

That said, Bubba at your local track or autocross may still like to see the vent.

You should never use a non-sealed battery box and a 4AWG cable is too small. That is the size cable the factory uses for the short length under the hood. For the long cable you must run from the truck, a 2AWG cable should be considered the minimum size.