Let me ask you. Premium sound was$1500, it did include dsp processing and wiring including speakers in trunk area plus extra tweeters in rear passenger compartment .
Now once u change ur std hifi system, with your custom, may I ask your configuration, plus cost of parts and labor? More so, now your audio system is not under BMW warranty I guess, so what sort of warranty we may get for after market?
Thanks

my X5 was a demo model, came with base audio system.
Total spend <$2000USD, my labour 5hours.
Aftermarket warranty is as good as the quality of equipment you buy, which is better than the crap that came in the X5 with base audio.

Thanks Barney. I have already spent, $1000, for parts and labor for BAS stage 1 speaker upgrade. Now where do I go from here???
Did u install trunk speakers too?
How about DSP?

You could see if BSW offer an amp upgrade, with OE connectors.
I replaced the front door 4", added tweets, replaced underseat woofers, with OE plug n play connectors and wiring from musicarnw.com. Output from headunit is connected to JL Cleansweep processor/equaliser, from there to amplifier and back to speakers.
I left the rear doors as is, they have little or no impact on sound quality.

I am waiting for that