Just wanted to say I love this thread, even though the Big 3 still hasn't helped me...
I have an '89 Acura Legend and I'm trying to run my meager system (200W MTX amp pushing one 10" sub) but my amp has been cutting out/turning off. The car has a 70A alternator, and the battery is good. I didn't think anything was wrong with the alternator, seeing as I just got it replaced in May of this year after the last one died after 5+ years of use.
So, I considered getting a capacitor, but after coming to this site I found that it might not be the best thing to do, and decided to do the Big 3. Cost me about $50-$60 getting the necessary tools described in this thread, and I used 1/0 gauge wire. Hooked everything up, and still had problems with my amp cutting off.
I go to Autozone and Advance Auto and get my battery/alternator checked, and everything seems good, except for the fact that my alternator seems to be outputting only 4.8 - 10A. Holy crap, I don't see how my car is even running... or charging my battery. I'm going to go back to the place that put in the alternator, hopefully they will do something about it.
Anyway, just thought I would share my story. This site (and especially this thread) rocks. Lots of helpful ppl here.
I'm open to any suggestions.