new alternator for audio system?

I am gettin a sound system installed in my car (2 10" MTX subwoofers in an audiobahn enclosure, and an Aura Force 400Q-A amp) and i was told by a friend that i needed to get a heavy duty alternator (that cost 400$) to power my system. I have a 2001 Honda Civic and he said that you have to replace the factory alternators and get a heavy duty one to power it, because if you dont it wont work. is this true?? and does anyone know anything about systems, amps, etc??

It's not necessary. I doubt you will be pulling enough power for that to be a problem.

only replace the alternator if the OEM one can't keep up

I dont know if you have installed ur sysem yet, but i say stick with ur stock alt. and get 1 or 2 fared capasitor, works like a mini battery, so it holds charge so ur battery doesnt have to use so much juice