I am thinking of buying used premium sound system from ebay. The package seems to include all the speakers and amplifier but no harness. Did anyone try to do this before? Will i also have to change the head unit since that is not oncluded. I now have performance sound which is terrible and doesnt even include tweeters. Premium package seems like a good deal, but i am having second thoughts because i dont know if it will work. Any help would be greatily appreciated.