Can I replace the stock 12v battery with a more powerful battery. Example I want to put in a XS Power Battery. It has more power storage capacity but I'm wondering if that will Thu you charge with the hybrid system or the system stops charging the 12v battery when it senses is full which would be stock level of full. Anyone know if it is safe and effective to replace sock battery with better battery?

Thanks

 

Go for it!

 

The 12V system and the hybrid system are isolated from one another. You likely will not benefit from putting in anything more powerful than the stock battery because the Hybrid does not have a traditional "Starter" and does not need the 12v battery's "cold cranking amps" to start the vehicle. The 300V system starts the vehicle, the 12V system just tells it to do so.
XS power batteries while awesome for extreme audio set ups, are still lead acid batteries which I abhor, I would recommend a "dry" battery, Spiral wound (Optima Style). My dry battery is going on 4 years here in Arizona which is amazing because lead acid batteries rarely last more than 12 months due to the punishing heat here.
If you have extra money to throw around and want a battery that you can show off to friends, check out Braille batteries, They have batteries that cost up to $3500(but start at $150) and they are truly the best money can buy.