Sound options without HK

[pimpmycode]

Unfortunately i took too long to decide whether or not i want the HK loudspeaker option on my new 123d M Sport Plus.
As a result the dealer says that it's too late to add this. Although production has not actually started he says it has a 1200 status code and the order is not amendable.

So reading up on my options once the car arrives in May, there is the Alpine retrofit which is better than the standard stereo 6 speaker system but kind of seems like a sorry excuse for not getting the HK. Then there is the custom install option which might void the warranty.

If i change the speakers in the doors, add tweeters, change the subs under the seat and amp them all will this void the warranty? I would prefer leaving the BMW professional radio i will have.

Are there any other options to improve the standard sound without messing with the warranty and changing the standard look of the interior?

Is it possible to buy the HK loudspeaker equipment and have that installed?

[taibanl]

Check out the aticky on e90post. Should get you started.