[Viffermike]

Some advice, from someone who has contributed regularly to the audio questions on this forum, who has some advanced knowledge about speaker placement, speaker types, and acoustics, and who understands where you're coming from in all regards:

1). You will need to address the underseat drivers if you upgrade the front speakers to components. Why? Because the first thing that ruins a tight, accurate, spacious soundstage is muddy mid-bass and bass frequencies -- which essentially become the same white noise that you'll be dealing with from road noise, tire noise, etc. Of the OEM drivers, the underseats are by far of the highest quality, so you can get away with their use for a time. But if you plan on doing what you're discussing, you will hear how deficient they are.

An axiom for any system, audio or otherwise: It is only as good as its weakest link. The underseats will be its weakest link when you are done with what you're thinking.

2). Raising the tweeters in a component system above ear level isn't recommended because tweeters are highly directional. The reason the sail-panel placement works reasonably well in most cars is because that's the best placement for them relative to ear level. Any higher than that and one runs into phase and projection issues that cause spatial disorientation regarding the programming. Since when should a pinch harmonic from an electric guitar solo, or snare drum and cymbal hits, come from above you, but power chords and fill rolls come from below you? That's the effect that I'm talking about.

To wit: Advanced surround sound systems such as Dolby Atmos that incorporate satellite speakers above the listening position rarely feed 'critical' programming (example: dialogue) to those speakers. They are specifically used for spatial effects ... which brings me to my next point:

3). The rear speakers are entirely optional and are essentially so-called 'fill' speakers -- just like rear satellite speakers are in a surround sound system. If you're interested in fidelity and true stereo sound, disconnect them.

4). Components are worth the extra money in a 2 Series precisely because the tweeters are able to be placed in a better position. As they are now, tweeters in a coaxial driver are not able to be aimed well; they're too low, and the dispersion of the one in the driver's door is completely blocked by the door handle. Not good. If you're truly interested in fidelity, components are a MUST.

Since you only want to do the doors once (understandable), I would start with sound deadening and the Morel Integra components (or whatever choice you end up making). Install all of that first, then re-assess and improve from there. Take it in steps. That's how I approached my upgrades, and I decided to stop after adding an amp (no DSP, stock underseats.)