my friend had a extra battery that he used for like 6 months in his jetta, he let me have it for some reason, my question is should i even use it (for my amp) its a Duralast that outputs 760 amps and 590 cold cranking...

sooo should i keep it or trash it

 

If you do use it remember that it has to be hooked up. This will put more of a strain on the alternator cuz it will have to charge two batteries instead of just one.

 

yea i know ill need a isolator, but should i even use it for my amp? or is it at least better than the stock battery (if so ill just switch it out with the regular battery if the amp dosent work out)

 

im almost positive its better than stock, but not 100%. I think the stock battery pushes either 500 or 550 cca's