For what it's worth, I started with the same stereo and tried to go down this same path. I did it incrementally, never being fully satisfied until my current setup. Started with BSW logic-7 kit and installed with all the factory trim panels + MS-8 and SWS-8xi underseats running off an RF P300-2 amp. This improved the sound dramatically, but still didn't sound good as the gap between the Earthquakes and what the BSW 4's could handle off MS-8 power was just too wide for me. I eventually got with VP Electricity and changed out the underseats to the Jehnerts, added his 12" corner mount sub and changed out the RF P300-2 to a JL XD700/5 (and added the crossovers for the front set).
I can provide pictures if you want, not sure how much that would help you at this point. I would caution against trying to get to the Logic 7 system, even with the MS-8 providing the logic 7 I now keep it turned off due to the bluetooth echo and the "stepping" it incurs when trying to process between channels at high volume (I can hear certain sounds noticeably stepping between channels as it changes the placement of the sound). Could just be me, but thought it might help to hear from someone who has been down this road before you.