Some of us who drive the early-VIN performance cars know of that "squishy" feeling when you accelerate aggressively through turns. The car feels like it rolls, and is missing a firmness in the turn that allows for more positive control in acceleration. Note that I'm not an expert in suspensions by any means, so I'm using the "technical terms". I decided I wanted to find something that would get rid of them. One owner was able previously to convince Tesla to do a partial upgrade to P85+. I wasn't interested in the stiffer ride of the P85+ so I didn't want to go the entire upgrade route either. I worked with the service center's advisor, who placed the order for the same parts for me. Apparently, it sent up a few red flags and a few folks at corporate reached out to the service advisor asking what we were trying to accomplish. Unfortunately, in the end Tesla declined to do a partial upgrade and stated rather decisively that partial upgrades using P+ components on an originally-delivered P car is not supported, and service centers will not (or no longer) do them. They will do a FULL P+ retrofit at a cost of ~$20k if you so desire, but not a partial upgrade. However, after consulting with Laurent and lolachampcar, I took a slightly different approach. lolachampcar suggested I just ask them to upgrade the car to the current production specs for P85 cars, with current-rev lower control arms and rear subframe -- that the replacement of just those parts would make the biggest difference in removing the squishies: The service center exchanged a few messages with chassis engineering on my requests, and they concurred that the idea would best accomplish what I want, with one other recommendation - a replacement of the upper links as well, which have been revised since the Sig cars. Chassis engineering signed off on the changes and the parts were installed while I was out of town last week. These parts are now common between P85 and P85+ models. I have to say that I am very, very pleased with the results; the car's ride remains as a sedan should be (so it's not a rock-hard ride) but the squishies are gone under hard acceleration in turns. While turning, the car hangs onto its rear end now. The price of the change was ~$5k including parts/labor. Here is the list of parts and the part #'s: Replace Subframe Assembly - Rear REAR SUBFRAME ASSY (6007012-00-E) 1.00 1518.69 1,518.69 Replace Control Arm Assembly - Rear - Lower - LH RR SUSP LCA ASSY (1021416-00-A) 1.00 318.60 318.60 Replace Control Arm Assembly - Rear - Lower - RH RR SUSP LCA ASSY (1021416-00-A) 1.00 318.60 318.60 Replace Link - Suspension - Rear - Upper - LH RR SUSP UPPER LINK ASSY (1021418-00-A) 1.00 212.88 212.88 Replace Link - Suspension - Rear - Upper - RH RR SUSP UPPER LINK ASSY (1021418-00-A) 1.00 212.88 212.88 A big thanks to both Laurent and lolachampcar for their help during the process. - - - Updated - - - One other point I should probably note: the service center used to fear having to align my car - they've had to do it several times in the past, due to various issues (initial alignment shift, crazy tire wear, machine specs incorrect, etc.) I was told that in past alignments, it could take them up to 2 hours to get everything aligned, and that in some cases, adjusting something would send everything else out of whack. After this change, I was told that aligning my car took less than 20 minutes and that everything adjusted very, very nicely. Perhaps my car experienced the same thing that lolachampcar saw in his earlier - the subframe having some weird situation to it that made things not line up quite right.