Sup ryan, man i've done EVERYthing, i've done everything you've listed and more.
i even did the ghetto looking, warping the 16 gauge wire on all the RCAs to ground that on to the HU. I've even bought monster 4 channel RCAs from frys, thank god for frys, takes anything back haha. i've tried another amp too. i called up my friend, he's an audio guy down to the core. he said it might be the deck cuase when he swapped decks out he said that he got the whine on a car that was fine before hand. his set up was working fine and when he swapped to a new deck cuase he wanted to mess around with it the whine was there. my friend said that alt whine is mustly cuase of grounding, so i was wonder if any other 6th genners get the same problem, if not it sjust my car.