If you have a proper garage and a bit of courage you can have brilliant sounding system in around around £1300.
I fully understand you don't want to do it yourself but if you hire a guy to do it all for you. Atleast you can project manage and choose and pick the right part.
IMO none of above options were looking good to me. They will achieve good result though but you can get similar good result by just installing tweeters.
650i F12 - HUD, 6WA, SLI, Logic 7, Dynamic and Adaptive Drive, Comfort Access, Soft-close, top-view,
Previous X5 40d M Sports and 535d LCI