A lot of what I am reading here is false, and contradicting. Not trying to crash this party, but I think it's important to note that virtually all of the HK systems use the exact same drivers, subs, and tweeters since 2010 per realOEM, save for a handful discrepancies here and there. Sorry OP
The HK amplifier is basically the exact same in every G chassis car, 65129832609. The only outlier seems to be the 65129826944, which can only be found in the 2015-2020 5 series in certain, undefined circumstances.
Speakers DO actually wear in over time, so they are just like "shoes'. They become more responsive with heavy use, and that's a big part of this. Sound is arbitrary, and a lot of your experience with the old one, or the one you own sounding better in your mind is just rosy retrospection. It's fair to say, cabin to cabin, a 3 5 or 7 will sound different due to the interior space. But plenty of other factors come into play, like sunroof open or closed, which leather option you chose, how many people are in the car, background noise level, audio source of course, and many others. Maybe there are slight tweaks in HMI software changes, but even that HU version varies greatly car to car and I can't say BMW has ever changed much there from any of the cars I've experienced at our shop (lots). Again, there are some oddball part numbers here and there, but BMW, Phillips, nor HK went out of their way to design a magical, better, cheap 4" mid-range speaker and tweeter only for X model just because you own it/drove it and you think it sounds better. A different bracket? maybe. These are mass production partsbin-sharing cars after all.
Personally, I enjoy the B&O system the most from the F15/16 cars, with the HK being a close second. And it sure would be a lie if I said those pretty stainless speaker grills, and raising center speaker don't make me feel special, just like any desirable upgrade. BMW knows this well. I Haven't experienced the BW fully yet, but looking forward to it.
If you want better, more exciting (arbitrary) sound there are aftermarket options. You won't get too much bang for your buck nit-picking the three mediocre options BMW offers you. Blast your music, get your speakers worn in real nice, and find an EQ setting that you like.
https://www.klipsch.com/blog/how-and...r-new-speakers