I have a 2011 Terrain 6cyl with the "Premium" Pioneer 8 Speaker system. No dvd or noise cancelation. It doesn't seem to have much power. I would be interested if anyone has swapped out the stock amp with a good aftermarket amp and/or speakers. It seems like this would be a popular problem given the low volume sound. Is this difficult to do for some reason? Maybe a five channel for the door speakers and sub and leave the stock amp in for the 3 tweets up front?