And to that I say, "he's correct". I have "KATS" driving lights, MiiG H-4 conversion headlights, An Alpine 80? watt deck, and a 300 watt subwoofer amp. I know for a fact that all his stereo DVD player/moniter (equipment) does'nt come close to the amperage that I pull and I have a stock alternator, battery and electrical system. I never have a problem with all that stuff on at the same time, he has a newer car than mine and his electrical is probably more set-up for it.
I personally think his system will last for quite a while.
FWIW,
Dave.
P.S. decent install, I worked at "CAR-TOYS" for 5 years and have been doing car stereo stuff since I was 16. Not a bad install.