didnt really have time to read through all the posts, but my buddy has a 95 Camaro and had BAD voltage drop without a system. turns out he had an underdrive pulley on. it was so bad with his foot on the brake, he put it in drive and his lights dimmed and his voltage meter showed significant drop. we had fixed that though.
as for a system, he now has 2 12" MTX Terminators with the matching amp. hes running KnuKonceptz 4 gauge wiring, and experiences very slight voltage drop, under certain conditions. usually none at all. this system wont flex a windshield, but it is nice and loud. i am very pleased with it. i was never a fan of MTX, but they seem alright.