I am sort of new to the Lexus community i used to have a SC400 which i just drove but now i just acquired a 99 GS400 and i am looking toupgrade the already upgraded stereo. I don't want it to be as flashy as my last system in my JDM front Acura integra (pics below). I currently have an Alpine I300, 2 Alpine v12 amps and a Kicker free air sub in the rear. I am not really happy with this stereo but it will have to do for now until finish gathering audio equipment. My last car had 2 Kicker L7 10 inch subs, Eclipse AVN5435, 2 Kicker 600.1, 1 Kicker 350.4, Diamond Audio separates, XM radio. I loved this setup and never had any electrical or charging problems. I had an Optima yellow top in the rear for a cap and a Honda Optima yellow top for the rest of the car. I used 0awg wire throughout and i never had a dim headlight. The audio shop that installed it is no longer in business so i can not go to them for advice so here i am. I went to a reputable shop here in Atlanta who told me that for what i plan to run they wouldn't even begin to install it until i upgraded the alternator. Is this really necessary or do they really not know what they are doing? I plan on running Eclipse AVN6610, Eclipse IPOD adapter, Eclipse Sirius adapter, JL Audio 10w7, JL Audio 500/1, JL Audio 300/4, and possibly Focal speakers. Do i really need to upgrade the alternator or look for another quality installer?

And now old system pics:









and one of the car it was in