I'm one of the few that actually knows what you're talking about. You're referring to the 20" sport wheel package on Tesla's Shop, right? Well, the reason they need to upgrade your suspension is NOT to increase handling performance, it's to make room for the bigger wheels (told to me by Tesla service who installed them for me).
I got the 20" Sport wheels, but only had the suspension updated, because I won't need the wheels on the car until summer. My car is on my 19" Sport wheels OEM All-Season Continentals for winter. I'll start buying performance snow tires once these OEM tires wear out.
Anyways, I digress. The suspension update for me with the same wheels before and after didn't make a noticeable difference, so don't expect anything from it.
For me, the 20" wheels were worth it because I prefer summer and snow tires over all-season tires and I wanted to buy an extra set of rims anyways. Might as well get the 20" summer wheels for $500 more.
The continental tires feel too squishy to me coming from my A-spec stick TL. I haven't driven on all season tires for 10+ years. When you go to summer tires, it's a whole new ball game. The sidewalls are much stiffer, and the rubber is more sticky. That equates to very responsive, solid feeling cornering. If Tesla sold the 19" wheels with summer tires, I'd consider it. The 20" tires are slightly more responsive due to the fact that the sidewall is stiffer because of a shorter tire depth, reducing the amount of travel that the sidewall can flex. BUT, the 19" wheels would likely perform better at a track. From what I understand, you're quicker on 19" wheels over 20" wheels. Honestly, I love the feeling of corning (I live in Boulder, CO) and don't care much about tracking the car, so the 20s are a better fit for what I'm after. Plus, I think they look better. Damn sexy. I powder coated mine black. Can't wait to put them on!
P.S. I prefer OEM wheels over aftermarket wheels because I know the rim is engineered perfectly for the car. I don't know if that's true or not, but being lazy and just wanting to move forward, it sounds logical to me
Plus I think they look great and I love the black center cover, especially since it's likely engineered to increase range. I think it looks cool, especially knowing there's an engineering reason behind them. Standard rims are boring. Too much silver. I'm not a fan of T-sportline's wheels or the aftermarket turbine wheels. I think Tesla's look and function the best.
I stated a lot of knowledge and opinion here, but I'm open to criticism if you think I'm wrong. Maybe I am.