"Most high-end Audiophiles now use additional batteries and/or custom alternators with increased capacity. There are also devices for sale which allow two batteries to be used, but cut one battery out if the draw becomes too great in order to protect it for car starting, accessory power demands and such.
Space in the Boxster is limited, so I think a custom higher capacity alternator has more appeal and practicality than either additional batteries or Caps. "
For what its worth, I am using the larger size of the Barille battery and have had no problem using it to drive two large outboard amps for the speakers and subwoofer to unnecessarily loud levels. No lights dimming on heavy bass lines, so I am pretty pleased by their performance for audio applications.
Ed
