The only way you will know the true amperage output is by taking it to a local starter and alternator shop and have them test it with a tester that will show the actual amperage output.
The regulator in the link would probably do you. Im sure that the generator will at least do 25 amps. Its not hard to reach that by any means. If all your adding is a PA then you will probably be good. Put in a good strong CCA battery and not some little something and that wont hurt either.
Ken
