I am about to buy used W222 facelift tomorrow. It is equipped well but the owner did not care about the music so he took standard speakers.
However, I think Burmester is much better so I would buy Burmester speakers and order installation.

Is installation complex, does it requires a lot of digging through the car, or it is just removing door panels and replacing current speakers?

I dont want to destroy the car and have a cracking sounds later by dismantling everything to install new sound.

 

I wouldn't buy Burmester speakers, I would take it to an audio shop and have them improve it based on your budget. The base audio in the US is the lower tier Burmester, and then there is a Burmester 3D option above it. I know in other markets there is a base audio below the lower tier burmester we have standard. That lower tier Burmester is nothing special at all, I had to add a sub to mine to get it to where I felt somewhat satisfied.

 

did you use stock amp for sub? Or new amp?
I have a JL audio 10 in a box ready to go.

 

My sub has an amp built into it, no additional amp.

The sub does make a big difference. The Burmester is clear but it lacks depth. I have ti fiddle with it some depending on the song, sometimes the bass is way too much and you have to turn it down for a particular track, which is annoying...but overall it helps.

I drove a new 223 and the base Burmester in that is great out of the box, so they learned from our complaints.

 

I would not consider the Mbenz Burmester even if it's retrofittable. The standard Burmester on the W222 is fine (not awesome) and for the same cost you can get much better sound system if you go to a good car audio/sound system store. The Burmester 3D is the only one that I'd stand behind as being excellent in the W222. The standard Burmester in the W222 is not even close to HK on BMWs (understanding that HK itself is not standard on some BMWs anyway).

 

I would say the Standard Burmester is similar HK in BMWs