Battery for 3 amplifier

I’m running 200watts rms sub and 300watts rms doors and I don’t see much voltage drop when playing loud. Funny thing I noticed... when the car is on and then engine is off the voltage remains 14.5, so I think the hybrid battery is keeping the voltage up when the alternator is not running. I thought about running super capacitors or even standard capacitor but I’m not sure how the hybrid system will take it, I have no idea how the charging system works on this car.

 

There is no alternator. There is a DC-DC converter which steps down the high voltage from the traction battery and feeds it to the 12v system. I've read in other threads that it's good for around 100A, not unlike an ordinary car alternator. That converter is active whenever the car is in Ready mode.

Look at what the amps actually draw vs. what they can supply. They already have significant capacitance in them to smooth out the demand bumps.