My factory speakers are going bad. I want to upgrade plus add a subwoofer in the wheel well of the spare tire. I don't want to add that speaker box crap in the back. I want to look stealth and stock. I remember that an RSX subwoofer can fit for the spare tire? Also I noticed there are tweeters on the front dash board as well. Are there other speakers in the back door? My budget is 300 - 500 dollars.