Got a 2008 Mercedes C300 with AMG mods today. It has the premium sound package and I assume factory speakers but it sounds very good, I mean really good. Good mid bass from the doors, and crisp tweets. The rear seats do fold down so I was thinking of one really good 12 " sub. What are your thoughts on upgrades? It has this head unit which is really nice but I don't think it looks to be special. https://www.pioneerelectronics.com/PUSA/Car/DVD+Receivers/AVH-X2600BT