Stereo sounds very good, but would be better if lower front speakers worked. When I bring the fader all the way forward, I just get the treble from the upper speakers, no bass from lowers. Tried two head units with same issue. Ideas??
The stock system has a pretty steep roll-off below about 100Hz, and swapping the front and back channels is said to improve the sound that gets to the front lows. There's a thread about it over at North American Motoring.