Depends on what you mean by stock system
YES
its the same year round
Cant you need a amp or you will blow the battery
No it will not damage sub unless its raining or something.
Woofers
Of course!
Yes, you can use a 5800-watt amplifier with two 12-inch 1400-watt woofers, but it's important to match the amplifier's output to the speakers' power handling to avoid damage. If the amplifier's power significantly exceeds the woofers' ratings, you may need to be cautious with volume levels to prevent overpowering the woofers. Additionally, ensure that the impedance of the woofers matches the amplifier's output specifications for optimal performance.
You cant just split the wire you have to go to your everyday audio store and get a step down
200 watts
Best Buy and other electronics retailers stock Pioneer sub woofers. The can also be found at Amazon and other electronics retailers on the internet such as Overstock.
One can purchase car speakers and sub woofers from most car accessories stores including Halfords. They can also be purchased online at Argos and Amazon.
you have to get an amp, crossover or an amp with a crossover built in and all the gear to install it like speaker wire power cable patch cords remote wire bow for the subwoofer that will fit the truck