I am by no means new to car audio. Many systems spanning over decades. Thanks to my Uncle. (God rest his Soul, Jim Fosgate) I have had crazy systems both in home and car. My last home theatre build I had 32 12" subs all hidden in the stage seating and in the wall. Now I only use 2 small 21" subs. So to say the least I am a little underwhelmed from the bass in my MX p100d. I would like to tap into the system and add a small amp and a more capable sub. The internet is crawling with M3 and MY even MS upgrade options. I cant find any on the MX as far as prebuild kits or what others have used. Have any of you put in an amp and upgraded the sub in the MX. Would love to know what others have done and what the outcome was. Thanks