I saw another CF diffuser on a glacier blue Roadster at Tesla HQ a while back. So I think the 2nd one did get installed / used.
The all carbon Roadster has moved around the Country with its' owner, but I think is in Orange County (SoCal) these days. I am surprised we don't see photos of it showing up on the exotic spotter sites. I guess the owner mainly uses it for the same commute.
The big brake kit works really well. It has a lot of suspension customization too. But in the end, I think there wasn't a good costs/benefits to put any of that into production. It would have been hideously expensive to make them in the small volumes that would be the possible market of Roadster owners wanting performance upgrades.