It depends on how much you love your sound.
If you do Hifi will not cut it , even the HK system is not IMHO audiophile quality.
Looking at replacing all the speakers and the amp possibly with 3rd party options for the HK system now :- Bavsound or Bimmertech
Again it depends on what your "ear standards" are and if you can discern good sound from great sound and whether it matters to you.
To me after listening critically, HK is not very good , the high frequencies lack that musical sparkle and is not very smooth and the amp does not control the midrange very well it's not tight.
I have a 2 month old BMW 330i M Sport G20 with HK 16 speaker system
I like female vocal and sometimes techno(lots of bass) so opposite sides of the spectrum, when I put the system up to high volumes it does not sound good , so HK is only for mid volume listening.
Also bass is just not there from the underseat speakers
So if you get the car you can always replace the speakers and amp to better ones, so dont let that discourage you from getting it
Good luck
