So I tried to add pkg 773 to my 2020 S63 Coupe at the last minute but the spec was already locked. Dealer priced out the parts but MSRP was about 2x the option cost, and they only offered a trivial discount, so that was a no. Ultimately I sourced the exterior carbon parts on my own at a nice discount online, then had my detailer apply PPF and install.

The front splitter and rear diffuser are OEM, purchased through a M-B dealer in TX that discounts parts online about 34%. As usual, delivery cost is high as there is no drop shipping available, but I was not charged sales tax since items were being delivered out of state. Online ordering was super easy, shipping was prompt, and packaging was great. Both pieces were about $1900 plus $300 for shipping = $2200. I thought the diffuser ~ $1200 was a relative bargain considering its size and complexity, but labor to swap was quite significant as the rear bumper had to come off and numerous rivets had be drilled out. These were replaced with stainless steel hardware (which is what Mercedes should have used in the first place for a modular bumper component). The splitter I felt was costly for it's size and simplicity at ~ $700, but at least was easy to install.

The OEM mirror bowls and rocker panel inserts were very expensive, even with discount about $6000 for all four pieces, so I went aftermarket.

The mirror bowls were purchased from a USA Ebay seller for ~ $200 delivered, <10% of OEM cost. They are in fact OEM plastic bowls with real carbon fiber applied to the outside, and LEDs were included so they did not have to be swapped. They look good, with the exception of the very thin visible housing lip along the front which remains plastic rather than carbon fiber. Note: Do not buy the cheaper 'carbon look' ones - those are garbage!

The rocker inserts were purchased from a Chinese Ebay seller for ~ $550 delivered, <20% of OEM cost. They are real carbon fiber covers rather than full replacements for the standard parts. Fitment was not quite perfect requiring installer to apply thin strip of black vinyl where the cover meets the car to completely conceal the chrome underneath. Luckily being low down this is not really visible and the result is satisfactory - see pic below.

 

Looks great ! I really like the rocker inserts.

 

Looks awesome! You do the coolest things, making a perfect coupe perfect-er :-)