Hello/AOA everyone, haven't posted in a while.
Quick update: I've had Dinan suspension for about 2-3 months now and it drove like crap, would float all over the road and did not feel planted at all and has a clunk on passenger side going over small bumps.
Diagnoses: It's been aligned by BMW twice and I gave them Dinan specs but they just wouldn't align per those and give me BS reasons that -1.7 camber at the rear will wear out tires much quicker (even though I told them I don't care about the tires, they just wouldn't) - I plan to take it to another shop to align per Dinan specs but for now I figured I'll tackle the clunk. Checked all suspension components and they are tight and nothing seems to be loose or out of order. I rested the case thinking it's the strut mount that may have gone bad or close to going bad that's causing the clunk but before I ordered them for $150 a pop, I thought to backtrack the process of installation, just to rule out that I installed them per spec and did not mess up in the process.
For the floaty drive, I was running incorrect tire pressure - I was running 38 psi on all corners (recommended on the door sticker), and after a little bit of research, I dropped it down to 32 psi and there is a significant difference in terms of handling and how planted it is now. Generally, tire pressure recommendation on the door is with full load (4 passengers + luggage).
Next I double checked spring installation steps against ISTA+ - during the installation process, I was more focused on aligning everything per original markings that I didn't pay much attention to how the springs/shims were installed. Luckily the driver's side installed correctly but I'm mainly messed up on the passenger side and that could potentially be the reason of the clunk. So I'll be fixing the passenger side (I hope I can do it without removing the entire strut) and the driver's side camber is a little out of spec, so I'll try to address that too.
Driver side is installed correctly - and if you notice the spring shim is seated properly and spring is sitting flush on the shim.
Whereas on the passenger side, upper shim is installed backwards and it's not sitting flush and the spring seems to be flopping around at the top.
So it's back on jack stands!